So the Hero Association classifies threats and Heroes according to their strength (manga/anime canon not necessarily game)
Threats- Wolf: unknown and weak threats
- Tiger: many people threatened
- Demon: an entire city and its people threatened.
- Dragon: multiple cities and their people threatened.
- God: humanity as a whole threatened.
Heroes are classed C, B, A, S
Class-B is expected to be able to work alone. Class-A is expected to be able to handle Tiger type threats alone. Class-S is expected to handle Demon type threats alone.
Threats are common daily things but heroes are pretty common. God type threats are rare. Presganging a kid into the Hero Association would be, hard to explain. You figure the S class heroes all 17 of them work full-time globally on Demon level threats and above. So pretty apocalyptic, but normal people live mostly normal lives most of the time.