This was a good concept and I liked it. The jumping is a bit too floaty, and input registration seems off (ground checks). I couldn't make it past the second level, kept floating lol, maybe increase gravity scale/weight to make it feel more responsive in the air. The ground checks could be a raycast in the fixed update to immediately allow jumping when on the ground.
If you wanna snazy up quick levels, I wrote a pixel level editor and am offering some itch pixel devs a pay what you want license. I am starving and would appreciate any feedback. love ur style<3