So I just tried this out. Some good things to say and some things that could use improvement.
First of all, I actually find the sprites kind of charming. They are well animated and fun to play with.
I thought the AI was actually quite good. It will jump around, and it beats the true test of a fighting game, which is if I can beat the game by standing in one spot and continuously punching, I'm not interested. You'd be surprised to know that there was a certain guilty gear game and street fighter alpha 2 which I did this on (on hard setting as well!)
I noticed that the "About" and "End" buttons don't work. While it's not too hard to close the program manually it's also pretty easy to add in a "close application" event. Also you should let people know what the controls are or they might not have patience to play your game.
Arrow keys to move - ASD to attack, and shift to jump.
There is no way to leave a fight once you've started. I would change that, and add a pause.
The biggest thing to sort out at this point is that after a fight is finished, it cant be restarted. It starts the last fight again with a little bit of HP left. So you get about 2 punches in and it's done again.
Also I noticed while jamming down the spacebar that it extended the other guys healthbar all the way across the screen.
All in all I think this is a cool little project, and I hope you keep on with it I'd love to try the next version.