I thought this game was really cool, this is a twist I haven't seen anyone do yet with the jump being less powerful over time. I enjoyed how some of the obstacles early on took away your ability to jump rather then just killing you, that was super clever and very much helped with the learning curve of the game! Some of the puzzles were really clever too, I liked how in level 15 you forced the player to not have a jump but still move around. I think level 19 was my favorite.
If you wanted to improve, adding some particle fx could help increase the game feel while still keeping to the simplistic style. Music would be a nice touch too.
Overall, fun game!