Yoo , this is my feedback:
- Graphics is simple but not that bad , style matches through the game.
- Character moves too fast and no coyote jump
- character jump is too low and it's kind of difficult to jump on boss head
- Boss fight lags too much as falling blocks keep changing their position horizontally somehow
- Health is way too much for normal stages but that's not too bad
- The sounds are funny , lol
- It's good all levels are unlocked from the start
- Text of the main menu is too big kind of , maybe make it smaller
- I like that you made the cover icon without ui and it's kind of goofy , at least you tried , but it's not very professional ( if you want to continue working on the game after the game jam)
and that's all , good job , work harder and you will be better.