Congratulations on your first game, really good job! This is definitely a strong starting point, and I hope you just continue to join jams and improve your craft. This was a delightful short game, I had a good time with it, and I found it very impressive that you even included full and fair bosses in your first project. I do wish the bosses had less HP and the player moved faster though. The pacing for a lot of the game feels too slow with the movement and bosses having too much hp despite their movesets not changing too drastically. But that's just balancing, and getting a feel for that is all about making more games and getting all types of feedback to your games
Very good entry!