Tbh, it has a decently coherent storyline. It's not like the events are completely illogical, it's just conveyed badly.
Invisible Dragon is born made of air, he's invisible, so no one can see or care for him.
Colbob, the lord of the universe, bullies him, because he's a generic korean novel villain, and that's what they do.
ID promises to get stronger and avenge himself.
He goes around the universes getting stronger, one day he arrives on Earth and starts killing everyone (the generic genocidal tendencies that a lot of these MCs have for some reason)
Decides to chill out and be a human for a bit.
Random aliens invade and he fights them off, specifically killing the ones that can see invisible beings first (actually showing some tactical awareness).
Goes around fighting more people to get stronger, finds a dude who he can't beat, so he runs away to train (as MCs do)
Trains a lot, and stomps the guy
Fights his also invisible brother, and defeats him
Keeps getting stronger, so he decides to conquer the multiverse (his final plan was to beat the lord of the multiverse, so this makes complete sense)
Genocides people for no reason (not uncommon in these novels tbh)
A dude (Duike) gets his father killed and promises revenge (another generic MC motivation)
ID conquers the multiverse and kills many lords of universes
Colbob trains Duike to help him out
ID fights Colbob and gets wrecked, but has a hidden trump card
Colbob is about to kill ID anyway, but Duike stops him and ID is able to kill him.
Duike reveals he let ID win so he'd be the one to kill
ID dies as a "hero" (MC being portrayed as heroic even though they're genocidal maniacs)
It's not that complicated, and it kind of makes sense if you take into account the tropes and clichés that most of these novels follow.