Really nice and original! Really loved the aesthetics too, and fits the theme quite nicely. The controls feel a bit sticky though. Maybe its because you're a slime.
For real though, it seems you put a little bit of anticipation into your jump animations, which is a nice principle to follow when it comes to animation, but it can make games feel a bit unresponsive and laggy. The squishing animation can be used as follow-through for landing however!
All in all, definitely loved the concept and it was fun to play. Great job!