I think it would be a lot more fun if you could have 2 or 3 active projectiles active simultaneously and maybe a double jump. A high score table wouldn't go amiss either. All in all it's a little too simple for my tastes.
On the plus side the music is fits, the art style is cohesive, it runs smoothly on my POS laptop and it's not buggy which is very impressive for a first game. I'd worry about adding new features if you make a sequel.