This is a great puzzle game. The design has a great blend between feeling open-ended while still having a structured solution, the pixel art looks great, and the music choices suit the game beautifully. Levels 1 and 2 are essentially perfect.
When it comes to level 3, in theory I love the concept of a cozy puzzle game which suddenly becomes a high intensity boss fight. However, I think the gameplay is too much of a shift from levels 1 and 2, mostly because it's now completely random. I think something like Captain Toad's boss fights would have suited this game better, where it's still a structured puzzle, you can just die now.
Overall excellent game, and I'd definitely play any future iterations you make. Great job!