It's a simple game which I like!
Some things that you could search and implement here:
- the jump is too floaty, there are a lot of videos on that regard to fix it
- coyote jump
- make the respawn faster to soften frustration and get back to action faster
- door seems a bit off by only having the trigger on the floor
- level design: make it a little more interesting. Think about the height of the jump and plan them based on that. It felt bad to almost jump for two blocks but not been able because it didn't reach the height.