This was an interesting little game. The graphics and music could use some work. But, in such a short jam without a musician or artist, it can be super tough, especially if it's your first! Also, I think you could keep the player tumbling if you let the player jump while on their head. I got stuck on my head a couple of times. However, I was able to get off it due to a glitch with the tile collisions. It seemed like the tiles had tiny gaps between their collisions that the player would hit. Did each tile have a collision box?
With that said, I feel like you could build some nice puzzles and exploration by having the player switching between multiple animals. Additionally, congratulation on completing your first game jam! You made a good effort and present an interesting idea. Keep up the good work!