Not an expert in platformers, but this one was fun! I liked that it was forgiving and very beginner-friendly. There are also nice elements in it like the slowly apart falling bricks. The "cylindrical topology" idea is also nice. You also managed to introduce all the features very well, so that I never was left wondering what is something. There was only one point where I was cursing: When I had landed well on top of the slime in order to kill it (Super Mario style), but it killed *me* instead. X-) Maybe a subtle warning sing there, somewhere ("Do not touch!")? But it's not a big deal, since one never has to repeat a longer passage.
I would polish the graphics a bit, as they are still super simple.
Definitely a fun game, congratulations!