Not a big fan of the focus on boss fights, but they are pretty cool. I like how all the bosses are distinct both in appearence and mechanics from each other. Their movement is also quite distinct; The "Pearl" boss specifically I quite liked, with how it moved its legs across the walls of the arena like a spider.
Some of them do feel like they have too much HP though; namely the "Python", which I feel like is a little too bulky for being the first boss, and "Rust", which I feel is a fight that just drags on a little too long.
I do like amount of air time you can get with the multiple jumps + floating. Like another comment said, it makes the boss fights feel similar to Terraria, and I'd say it works pretty well here. Although, I would've liked a variable jump height (holding down the key sends you higher than just pressing and releasing the key quickly), although for the most part the game didn't really need it.
Useful control information is not explained or taught at all. I was unaware you even had multiple jumps at first, which is a bit of a problem since this game seems designed around that. Also I do agree with one of the other comments here that using the shift key to walk slowly is pretty important for the "Rust" boss, mainly for the bullet-hell esque phases.
A small tutorial would've definitely been useful here. Also, just having some more exploration/platforming between bosses would provide a nice place to get accustomed to the controls, as opposed to trying to figure everything out in the middle of a boss fight.
Aiming feels weird on controller. It's tolerable on mouse & keyboard, but it still feels a little awkward with how the gun rotates towards where your cursor is at.
The story was a little vague. The opening dialogue was a neat touch, however I found the (an?) ending after dying to some mysterious-looking humanoid boss. It felt kinda abrupt for the game to just end all of a sudden like that. The art of the two characters was cool though. I imagine something different happens when you beat the boss, but still, it does feel a little jarring.
Also, I feel like the game was lacking in terms of... metroidvania-ness? It didn't really have much ability gating. But I suppose I do see the magical girl aspect to it, so it doesn't matter that much for this jam.
All the being said, the game did have good boss fights, and that was clearly the focus, so I'd say the game is pretty good. Good job.
Edit: oh also, this is a bit of a me thing but I feel like having some cool music playing during the boss fights would've made it a little less frustrating to die them over and over again. Not a big deal though.