Hi you have a very cool game idea but the level design does not help you, for instance if you take to much damage and have no hearts around you is game over and you need to reset, the camera in my opinion needed to show more of the level because when your player has that much speed and that much jump force spikes will show up so fast, and they will damage you, for me the only way was to remember the spikes positions. That worked well until I rage-quitted on the level 5, also here is a screenshot that shows a problem with this section of the third level:
For some reason if you touch the spikes in this part you will grow to big to get out, and if you get to the max size, the spikes don't do damage anymore like in the screenshot, and I needed to quit multiple times and start all over again.
I know that this is a review where I point out all the negative stuff, and I don't do that often, but the idea is so good and it's so sad that the game has these little things that made it less enjoyable.
I hope that you will update this game after the jam, and if you do I will gladly play it again.
Best of luck!!!