Damn, when did he become so strong? He isn’t human anymore.
Might be easy to miss because he has no technique and didn’t know how to fight, but he’s been fighting side by side with the girls since day 1. As of recent arcs, he was killing the mobs as easily as the girls did during their hunts (bosses aside). Also his “training” was him 1v1 against rare mobs and he had enough stats leeway to overcome his lack of skills and learn. Average adventurers would run away or fight as a party.
Based on that I would guess his stats and growth rate would be identical to the character from the game he played. Which would make him stronger than civilians and probably most run-of-the-mill adventures, even more so when gears are accounted for.
Tl;dr I don’t think his strength/stats was ever “human” of that world in the first place. (perhaps an upper tier adventurer?)