Kaze (my betta) jumps at my fingers when he sees them as it means he's getting food, I don't think there's anything aggressive there at all; I believe it to be a case of biting the fingers that feed you because you think there might be a pellet on the end of them.
He has and does bite me from time to time, usually if my fingers are hovering over him when he chooses to jump but it doesn't hurt, it tickles. It can take you by surprise but really they can't do any damage. I keep herbivorous insects that can do more physical damage to my fingers than my betta ever could.
I do not believe it to be an indication of aggression but rather excitement or anticipation, Kaze is a little softie and wouldn't hurt a fly (though he'd probably eat a dead one if it got into his tank).
And don't worry, no question is ever silly! It's good to ask otherwise we'd never know anything