This was pretty good! I think the landing sound was a little loud, but I really enjoyed the audio design otherwise. The movement felt good and I liked how the demo introduced each mechanic/design idea.
I suspect this game is going for more of a precision platformer which I'm usually not fan of because I find them too frustrating. So I don't know if I'll enjoy the full game, but I liked the demo!
Also, I would not describe the art style as retro. It's a modern pixel art for sure. It's got all them frames! The art is really great. Not only does it look nice but it communicates the elements very well.
Good luck!