Good job on putting your first game together and sharing it in this game jam! Hopefully you learned quite a bit along the way :) I have some constructive feedback I'd like to give on my experience playing through this:
1. Do not force playing to restart from the beginning of the game when dying. It's rude to the player's time UNLESS that's part of the game's core mechanics.
2. The player controls. The jumping was single-height and the left-right controls were very floaty. Even basic platforming challenges felt irritating to complete because I'd whiff past a platform due to the unresponsiveness of the controls. Again, this could be by design, but I assume that floaty platforming was not actually the focus of the game.
3. The final boss -- I think I did damage to him once (he flashed red), but I wasn't sure how to reproduce that again. There wasn't much feedback on if I was successfully hitting him until I saw that red flash once! If only I knew how to do it again...
All that said, congrats to you both on putting this project together! This sort of game genre is a very ambitious first step :)