Nice work! Especially for being your first jam. You should be proud!
As a big fan of music games and especially ones that don't just do the Guitar Hero thing*, I love the idea of the level visualizing and reacting to the music. That's an impressive technical feat as well. It'd be great to see the idea developed further, to the point where you have to pay attention to the music and plan around your knowledge of it in order to progress.
*Not that there's anything wrong with that.
A couple technical notes. The game window is really tall! Haha. I couldn't fit it all on my screen, even in fullscreen Chrome, without zooming out. Also, I'm not sure how I did this, but somehow when landing a jump I managed to get the guy stuck in the left-facing animation even as I was moving right, resulting in a moonwalk. It was awesome. I spent some time afterward trying to recreate it but could not.
Congrats on finishing a jam project!