Fascinating puzzle game which is, in my opinion, a bit hindered by its mechanical demands. Let me explain:
First some good things:
I was pleasantly surprised by the art first. Then the sound hit. That's a good laugh and I'm literally giving it a 5 stars on presentation from that alone. You are bold, I'll give you that.
Controls feel good and character movements are alright actually. For something with platforming elements, it's important to nail those down and you've dunnit!
My main caveats:
As a mainly puzzle-focused game with platforming mechanics required, I think your design decisions may have some mishaps. In level 3 and 4, you've stated that the opposite slimes can jump off each other, which is a fine mechanic on its own, but it still requires precision that typical puzzle players may lack. Your level 4 solution is a very literal example of that, requiring mechanical timing and precision to solve a puzzle.
In other words, the players may know the solution of the puzzle, but be frustrated that they cannot execute it. This is an issue I've faced previously and am trying to design accordingly to avoid it now.
Overall, a pleasant surprise. Good job!