Awesome submission! I definitely get a lot of "Sonic-like" vibes from this one: go as fast as you can, jump over obstacles and clear it as fast as you can, which is awesome to see! Slime guy is pretty cute, and the art fits well!
As Brad mentioned there were inconsistent ramp/hill jumps and often placed ramps in parts of levels that seemingly didn't give the player the utility they need; some geometry in the platforms I noticed also had little bumps in their colliders that sometimes halted momentum and/or took away the second jump. The game also could've benefited from some sound effects like a jump effect.
However, I do like that feeling you created of cleanly clearing obstacles in segments, it's a great feeling! Solid game!