Uhmm, Erza is widely known for
exquipping instantly , both armors and weapons. But apparently the villains "let her" exquip because of PIS and to "save page time". If that isn't a ridiculous argument, then I don't know what is.
Also the very images you posted proves she can exquip instantly.
Here her armor is shattered from Ikaruga and
here Ikaruga presses her advantage with another slash, only for Erza to exquip mid-slash into Flame Empress and deflect the attack. If C.Human doesn't have a speed advantage, he isn't hitting her without armors. In that other image you posted is Erza in her towel(?) thingy. Just as Jupiter fires she exquips into her defense armor to take the blow. Just as she's mere feets away from her opponent, she switches armor and blitzes him. Also none of her opponent's have caught Erza mid exquip so that argument isn't gonna fly.
Now about C.Human's "tactical advantage". You're greatly overestimating that. The combined human is as smart as the total population of humans to have ever lived. Now how much of these humans have intelligence fit for battle? A very select few considering the whole population. Also if someone is gonna be at a disadvantage because of no knowledge, that would be the Human. He's never faced anything like Erza, he's never seen Magic, flying swords and all that stuff so there's a very good possibility he's gonna get skewered because he doesn't expect the swords to move like that, especially when Erza uses telekinesis.
and humans can survive some elemental damage, seeing as he has everyone in humanity, he would have those rare anamolies where they aren't affected by such things.
There are rare anomalies that make people unaffected by fire, by lightning? What? There have been people that have survived a lightning strike, that's true, but unaffected? Hell no. They've been either paralyzed for life, or their nervous systems has taken significant and permanent damage. And this still doesn't include slashing attacks with wind and water. Also if you're going to use that "he has anomalies" argument, I'm gonna say the Human is mentally challenged and can't walk properly due to genetic defects with extra chromosomes.
Also she would have no way of using magic as there is no ethernanos in the air, this can be seen because in Edolas there was none and unless she has one of those pills, she can't access her magic.
I will not even try to entertain this argument.
Anyway, Erza wins due to far superior equipment, weapons, versatility and the Humans lack of knowledge on her abilities.
