Pre-quirk Quirks?

The basic idea is that someone, most likely Izuku, finds some old books on Mythology and becomes interested, searching for any information he can with it glueing to his mind. Problem is, the Dawn of Quirks caused a LOT of damage to records of humanity, and most ancient history and myths that didn't hold major religious significance, like Kamis and Christianity but not most yokai and folktales, were all but destroyed, international or otherwise. This Izuku is nothing but determined tho and scrapes together a surprisingly detailed log of myths and legends. He becomes a researcher and historian instead of a hero.

This doesn't mean much until a villain, AFO, creates some means of traveling space time, and attempts to go to specific locations in the world's history and mythology. Heroes learn that AFO believes these "myths" were humans and animals with absurdly powerful quirks, planning to steal them.

Enter the heroes, who now can access AFO's means of travel, quirk or mechanical, request Izuku, the world's current "expert" on mythology, because there are barely any experts and most of them are looney as shit, to travel with them to the various points AFO plans to visit so they can at least not jump into everything blind.

(I like the running gag of the heroes who, despite knowing literally nothing about myths and monsters they will encounter, underestimate the beings they encounter and get stomped by them before admitting they need help)