This is very, very impressive. I can tell that you put in a lot of extra time, which is the only negative thing I can think to say about this game and the only reason why I didn't give you full marks. It feels very polished. The controls are tight, the art is good, and the music is enjoyable and subtle. I especially love the slowly scrolling parallax backgrounds and the shattering effects on enemy death.
You did amazingly well. Try in the future to limit yourself closer to the 3-hour mark by picking an idea that's feasible in the time-frame and focusing on the most important features first, allowing other aspects of the project to be 'wants' instead of 'needs.'
I'm really curious to hear what your game jam experience was like. I hope you had an enjoyable time making this beautiful little gem of a game.