Overall great game! I enjoyed the mechanics and there's definitely a lot you can make from them. I had fun solving each level!
If I'm to give any complaints, as a composer, I think sound design felt a bit off. I think using piano notes as your "jump" is quite unique and interesting, but it often clashed with the music. I often write music to blend perfectly with the sound design. If the music covers up the in-game audio (or vice versa), then it's better to rewrite it to better compliment each other. Again, unique concept, but doesn't blend very well with the background music.
Also, I found a hidden flower and ended up beating the game with 11/10 stars. Was that intentional? Haha