Nice work! I played this to the finish, great artwork (love the Metroid vibes on the bubble platforms), great music, and the item mechanics and puzzles worked smoothly and were fun to beat. There was a good amount of gameplay, too.
It's also an unusual game in that the principal challenge of the game (and cause of almost all my deaths) was overcoming the momentum in the character controller. Small movements can be done under perfect control, but pushing a direction for a bit longer gives you a long continuation of momentum after you let up on the direction key -- longer than what I typically see in platformers. Jumps have to be hit "flat", so that you're not pushing in any direction on or before landing. I could see that this could frustrate some of your players, as it's not what platformer players are used to, but perhaps that's just a convention and not a reason to change (after all, over time I adjusted to it and it made the game more challenging, and challenge is good). In any case, I thought I would mention it in case that's helpful feedback!
Nice work!!