I like the idea of getting killed to gain abilities that helps you go through the levels.
There's two things that were kinda frustrating and that I believe could be easily fixed. First in level three, the water enemy got stuck under the level so I got stuck and had to restart. Most importantly, a lot of time the player slides of platforms since your platforms have really rounded corners. I believe that the artistic direction should never be detrimental to game design, so definitely something to look for if you wish to make your game better :)
Overall nice try and nice art !