I didn't beat the game, I got until the level past the puking frog. It is pretty difficult (at least for me).
The art looks really nice! It looks very polished, my only gripe with it would be the varying pixel sizes. Everything is pixel graphics, but the pixels themselves seem to be different sizes of pixels which makes it look off. The camera also didn't seem to be pixel snapped. This is just a personal preference of mine though, it's just faux pixel graphics as I would call it, as nothing is actually aligned on a fixed pixel-size grid.
The gameplay is good, but I found myself dying a lot from bumping into enemies. The character feels rather fast compared to their environment, and I feel like that results in missing jumps and often accidentally bumping into enemies. What would help for the jump timing is if there was more time to adjust the character in mid-air to help land the jump. The game requires precise inputs right now to land it or miss it. But! If it was your goal to make a precision platformer, there you go, job accomplished.
The potion 'slogans' in the spellbook are pretty creative, so props for that! I think the idea of having potion brewing as a way to do ability unlocks is a creative way to do it.
The background music was really, really quiet. You mention there's sound design but I heard very few sounds in the game, how come? I feel they would've made the game more lively and enjoyable.
Good job on the submission. Maybe it's an idea to touch up the parts you didn't have enough time for and make an updated release?