I really hate the 'super overpowered but thinks he's weak or average' archetype. It always feels so fake. like with the fireball, he saw it create a huge explosion. he hears about a big explosion, and thinks "I hope it isn't a natural disaster". His reaction should be to keep it a secret or say something like an apology. no human being would not correlate that they made a big explosion, and people saw a big explosion. and that's the exact problem. When a character acts like this, they either feel braindead or like a douchebag. it's ok to be humble, but only in moderation, and definitely not to the point where it looks like idiocy. I'd honestly prefer if he's a cocky douchebag because then he at least has the capacity to understand cause and effect and correlate events.