For a first jam, this is very good, nice work! I liked the art and the use of the preexisting assets, and I did like the music and sounds. I do wish the plot were integrated a little more (maybe with some lava?). Everyone's already mentioned the slippery controls, so I'll skip over them and the fact that the idea could've been used a little more.
The problems I ran into were mostly in the art, actually. While the art itself is pretty good, the color flipping was way too abrupt and hurt my eyes, same with the white flash that happens when you start (or restart) a level. I also ran into a minor glitch where the death animation played again when you were hit while the animation was playing.
I also ran into a weird glitch in one of the earlier levels (I want to say level three?) where the doors let me through without having to hit a button, making the level much easier.
Despite all that though, the game was still overall very good! You definitely have a ton of potential!