I like the direction you are going in! Some things i think might improve the game are hit markers of some kind, i know the slime reacts to being hit but when hitting multiple times during that animation its hard to tell whether they are registered or not, I also think messing with the run speed would be good, with the current world lay out running is a little slow, i see its in unity so if (for example) run speed is set to 3.5f you might want it to be 3.75f just to give it a bit more of a responsive feel to it. I think the gravity should be a bit less it feels like you fall very fast which can make some platforming very difficult when it shouldnt be, and the invincibility frames feel off, i cant quite say what but it feels kinda like you still get hit even when its not saying you take damage. Other than those things i think you are doing great and am hopeful for how this game turns out :)