Thank you! I don't know if I made it too obvious, but by killing slimes you can level up. In the updated version, I'm also adding hard mode (where slimes DO attack you), and I might add a shop where you can buy skins or something like that. I've also already fixed the jumping - I will just release it when the jam is over.
When it comes to pushing the slimes, I thought it was a funny little addition, but tell me if you think I should get rid of it.