The thing is, art, level design, and programming are all skills which you get better at with time. And, no matter how bad you are at them, you will always think you're worse than you are(That's my experience anyway).
If you want to be able to do something, just try it. It's as simple as that. If you want to continue complaining about not being intelligent enough or whatever, fine, do that, but you could be spending this time learning to program, instead of wasting it on arguing about how good of an artist you are.

EDIT: Just read Primpy's most recent post... I give up on this conversation.