Fun nice platformer! Good job with handling the scope of a 3d project and finishing it! I have some tips for improvement. Slimes and Shrooms you might use the “Shade Smooth” in Blender. Adding a water shader. There is a basic one on godot shaders. Adding a procedual sky to the environment node and adjust the colors of it.
For the gameplay the only issue I had is that I have to move on the clouds. (I would expect them transporting me)
Hope that helps and good job again, was a nice entry!