The biggest problem with the game in my opinion is that the controls feel really clunky and needing to start the level over because you failed a blind jump is pretty frustrating. Puzzle's are pretty easy, but the clunky controls make them feel pretty annoying.
If you want to make the game better I would advice looking at the https://gmtk.itch.io/platformer-toolkit and adding coyote time. I would also recommend leaning more to the puzzle elements and less to the platformer elements