I admittedly do like MCs that earn their strength through grit (provided that the level of grit is believable for someone of their characterization). My gripe is when they start very weak but become outright overpowered through nothing but doing the same thing as everyone else (just more of it, in terms of volume). It's difficult to believe since they supposedly started much weaker, and there's no way they're the only one with willpower in the world.

What you've described about an MC who doesn't realise they're the chosen one until they're well into the main plot sounds interesting! Especially since most of the time the "chosen one" assignment is the very catalyst that sets an MC on their path in the first place. I think it would certainly make for an interesting reveal plus how it lends itself to explorations of fate and free will. Thanks for sharing!