Amazing style and concept, I was trying to think of new ways to iterate on it than just "you're stuck going forward, go back" and it's pretty difficult to come up with new gameplay, but if you're creative enough to come up with this much I feel there's a lot of potential you can unlock.
Definite critique on the music but the audio of jumping is pretty good and the music style isn't bad per se, just too short of a loop.
Edit: I just saw in your trailer how the music was meant to be implemented. That's a great idea, still probably needs a longer loop but would've helped with variation. Probably proved tricky to implement.