Congrats on your first game jam! A meta-tip for game jams is having a browser version of your game is really important, because it makes your game available to the most people -- I would have skipped over your game if you hadn't commented in my thread since I use Linux. Since you commented I went over to my wife's windows PC and downloaded it, but 99% of the time I wouldn't bother to do that and would have moved on to the next browser game. Since you're using Unity, exporting a browser build should just be another few button presses + maybe some extra debugging, but it's definitely worth it.
Gameplay wise, I was a bit confused about what to do -- I noticed my health ticking down the whole time, so I tried waiting until it went to 0 and I got the win screen. Then I tried exploring the level, but I couldn't figure out if there was anything I was supposed to do to get a different ending -- I got down to layer 3 by falling through the lava a few times, but died due to my health ticking down before I could get farther, so not sure if I missed something. I think the lava works well as a failure is progress mechanic since "failing" to jump over the lava and falling in is actually how you progress to the next layer, but there maybe could have been a bit more around that -- maybe the levels make it progressively more difficult to fall into the lava?
I liked the art and the music, and while the movement was a bit floaty I think if the speed was cranked up a bit it would have felt pretty good for a floaty platformer.
Overall, good job for a first game jam!