How Jin Wins this: A note on their levels of SS:
It is currently impossible to quantitatively prove that there is a meaningful difference between Superman's SS Level and Jin's SS level. Superman's SS feat is weird to begin with and he did it with some difficulty, and all of his enemies and allies on this site scale to him, so attempting to scale them back is not an argument. Jin has gone through numerous massive power increases both before and since his exhausted, dying, limbless clone did the Small Star level feat. Starting at peak condition and with Na Bong Chim limit removal X250,000 this means he is squarely into SS level. Additionally, while it is true his Na Bong Chim limit removal is what is pushing him (well) into SS level and only lasts for 5 minutes, these are characters moving at MFTL+ speeds. That time is not a problem. Also, sorry @AnonymousOtaku, but no, Jin cannot keep multiplying his power. He's never been seen to be capable of stacking them and to assume he can is NLF.
Reason 1: Jin's Clones One of Jin's main advantages in this fight is that he can summon 100 clones of himself who are all capable of utilising 100% of his power and weapons for 5 minutes, possibly longer (Jin's clones are stronger the closer they are to the original. Hui Mo Ri, who gives us the 5 minute limit for 100% is in a different universe to Jin, about the farthest away he can get. Also, see the note above for why this time limit doesn't actually matter). These clones also gain all of Jin's knowledge upon creation, and upon being defeated give Jin all knowledge they have obtained, allowing him to experience and adapt to Superman's attacks and abilities without risk.
These clones can also be created several dozen metres away from the original, allowing them to be summoned all around Superman to surround him and attack from all angles. Effectively this means that Superman now has 100 more SS levels beating on him at once. This include Endless Thunderbolts,RJ strikes, acupuncture attacks, and everything mentioned below.
Reason 2: Jin is Friendship and Friendship is Magic
Jin is a demon who became a Buddha who became a god from the sage realm, who reincarnates, and is both a source and user of Charyeok, the G.o.H's equivalent to magic. I'll quote my previous reply for the rest of the explanation.
"Charyeok is borrowed power, which comes from gods and spirits, such as Jin Mo Ri. It is never once attributed to any form of science or scientific process. It can achieve miraculous feats such as summoning and manifesting the spirits of dead wariors, granting any wish, manipulation the fundamental forces of reality, empowering beings, absorbing the life force and mind controlling of beings such as monkey and ox demons, creation and matter manipulation, opening portals to other worlds, etc. Charyeok which causes all of this is treated as magic and is the God of Highschool verse's equivalent. All of Jin's abilities are magic, and as a magical being his physical strikes would also qualify"
Also, @XBlack, magic is a method, not a result. All the examples of what it could do that I gave you above are all achieved through magic.
Superman is consistently shown and stated to be as vulnerable to magic as any normal man. His durability, caused by a solar powered bio-electric field around him, is disrupted by magical attacks, allowing them to bypass his durability. While he has shown some resistance to magical attacks before *cough blatant pis that disregards the limits placed on him before for the sake of giving him the win cough*, it is not at enough of a level to protect him from 100 magical SS level Endless Thunderbolts from the Kinto-Un.
Reason 3: Jin is the Superior Fighter
I'll quote my previous comment on this, and add some other stuff. "He's done nothing but training and fighting other gods and monsters (most of whom are excellent martial artists themselves) for thousands of years, he's capable of copying the physical techniques of any humanoid opponent after seeing the technique once, in this incarnation he's mastered renewal taekwondo, and learnt techniques from karate and moonlight sword style, takeon, acupuncture, etc, he can see your weak points just by looking at you and block your blood to make your limbs useless with pressure points, etc" He also developed counters and remedies to all of the weaknesses in the style he had learnt, something even the original creators had been unable to do, can read the intent of his opponents once he is in contact with them Superman has trained in martial arts as well, this is true. But he is still well below Jin's level, having not even trained 50 years to Jin's 1000
Reason 4: Jin's Gourd
Jin's Gourd is capable of sealing and attack absorption. All he needs to do is say "Gourd, seal" and Superman will be sucked into the gourd. While Superman could escape the pocket universe inside it by creating a hole in space-time, there is no evidence he can direct the hole, and is therefore just as likely to open a hole to some other random universe, which would be Jin's win via BFR.
Any ranged attacks Superman has, Heat vision, freeze breath, throwing rocks(?), Jin can once again say "gourd seal" and the attack will be sucked inside the Gourd, nullifying them.
Reason 5: Ruyi Jingu is OP
The RJ is capable of extending intergalactic distances near instantly, and expanding to have the width of a small country. Its density does not change with this expansion, so it will always be as durable as before. Although stated to weigh between 7000 and 8000 kilograms, this is a reference to the Sun Wukong mythology and is incorrect, seeing as Uriel (who could near push the planet Mars away from the planet with minor difficult) had her arms ripped off when she tried to carry it.
The expansion properties of the RJ also allow for a degree of durability negation. In his fight against Jae Kal Taek, Jin utilised this by expanding the staff fast enough that it pierced through Jae's chest, then expanded it, ripping Jae in half. He utilised a similar method again in his fight against the First Crown Prince, repeatedly attacking him with copies of the RJ (yeah he can make copies of it, just like his clones. These copies all keep the same properties of the original even when broken, apart from their durability which is much lower) and shoving a fragment of the broken RJ's into a wound, then expanding it. Jin could just as easily do this to superman, especially if he has his 100 clones all attempting it at once, aiming for superman's mouth, nose and ears.
Minor other reasons:
Kinto-Un / Flying Sparrow Cloud
It can act as a shield against Superman's strikes. It can strike Superman with hundreds of lightning bolts at once, which when done to Jae's ascended god form, was able to reduce him to cinders and scattered body parts. And of course, every clone can use their own.
Ruler of the 7th Heavenly Realm
Serves Jin after he defeated it. Can be summoned instantly. High-Mid to Low-High regen. Flight. Offensive Shapeshifiting. Can distract Superman and attack from multiple angles, distracting him
Disputes against Superman's Abilities / How Jin counters them
Heat Vision
Grudge and XBlack have been arguing that Superman's heat vision is ignores durability via atomisation. Black provided one scan of Superman saying his heat vision works on a molecular level, which proves nothing as all heat works on a molecular level, that is literally what heat is, the molecules of something vibrating due to having lots of energy. Grudge provided a scan of superman overpowering Captain Cold's absolute zero beam, which also doesn't prove atomisation, because as I said in my previous reply:
"Absolute zero is a temperature. Absolute Zero is durability negation, because it means atoms don't have any energy so they lose their ability to hold themselves together so they collapse. Cancelling out Absolute Zero is just putting energy back into the system and heating it back up again. Absolute zero is not some temperature equivalent of a black hole that sucks in and negates all heat. Superman using heat vision to cancel out absolute zero is literally him putting the missing energy back into the atoms by heating it up. It doesn't show durability negation or atomic annihilation or anything. It's literally just him heating up the energy less atoms."
Grudge also showed a scan saying how Superman's heat beams were off standard scientific measures, which also doesn't prove anything as A) this is fiction and most things of this kind are off standard scientific measures and B) nothing in there says anything about atomisation or similar durability negation.
While it is possible superman could have atomised/vapourised/incinerated someone with his heat vision, I have yet to see any scans of him doing such a feat to someone on his own level and have concluded that any atomisation or incineration on Superman's heat vision's part is done via sheer energy rather than any form of hax, and would therefore not be able to one-shot Mori or his clones. Also, as stated above, Jin's clones can surround Superman and make it so he can't attack all of them at once with Heat Vision, at least not without depowering (via Solar Flare)
Superman's Flight
Yeah, cool, Jin's got that too. Superman won't be just flying away to roast them all with a planetary heat vision (which, btw, is stated it would take some time from that distance to destroy the entire planet with heat vision, so we can assume it's barely planetary level with such a width and distance between the superman and the target)
Enhanced Senses
Jin was able to sense the king fighting with Park Il Pyo from a different solar sytem, then fly over and intercept the strike perfectly. He can sense your weak points just by looking at you. He matches superman's enhanced senses
Ripping holes in space-time
Not exactly combat orientated. Again, if he tries to use it to escape the Gourd he's just as likely to end up in some other universe somewhere seeing as he can't control where this hole will lead.
Superman's Strength
Covered in the notes at the start
Speed
Speed is either equalised or superman blitzes, so I'm assuming it is equalised, nullifying this aspect of the fight.
Resistances to a bunch of things
None of which Mo Ri uses, so irrelevant
Energy Absorption Pretty sure this only applies to solar radiation. Even if it doesn't, Kinto-Un's lightning is magical and from a different universe even within the G.O.H verse, and superman has been shown to struggle or flat out be unable to absorb solar energies from different universes. Unlikely he'll be able to absorb it.
Superman's Instant Lobotomy Only works when superman is looking into the person's eyes, which is unlikely to happen seeing as A) They are fighting at mftl+ speeds with Jin/clones using martial arts, so Superman getting the chance to look into Jin's or his clone's eyes is unlikely, B) Superman doesn't know which clone is the real one to lobotomise, and once he's done it to one clone Jin will know not to look in Superman's eyes C) If Superman attempts to pin/grapple Jin or one of his clones to look in his eyes, all the other Jins are kinda going to take advantage of Superman's distraction.
Intangibility
Superman's saving grace, although Jin's ability to attack intangible Charyeok spirits could possibly counter it. However, I would like some more information on this. Is it tiring for him to use? Can he only keep it up for a limited amount of time? What sort of attacks have managed to attack Superman while he is using it (I assume there must be some, or else it would be a very OP technique to use)