Hi, here is my review:
THE GOOD
I really like the music and the atmosphere it builds. The backgrounds while AI, are still very pretty and I like that you disclosed it. Overall i think it's a simple idea, but sometimes simplicity is the best
POSSIBLE IMPROVEMENTS
The character animation isn't full and it's not synced well with the movement speed, making it feel like the character is moving slower then it should. Also while the backgrounds itself are pretty, they aren't super immersive (as in they don't feel like part of the level). I think it would also be nice if there was a more defined environment instead of floating platforms.
TLDR
I think it's a good prototype, but there is still work to be done for it to be a great game. Definitely achievable though!
Btw, I would also apprentice if you took your time to look at my own project :)