Certainly a good start!
You really need some prompts that say "Press Spacebar to Continue" because at times I just sat there, not realizing I could continue. Took me a minute to even get past the start screen.
I found it tedious to climb those stairs to pick my levels. Just being able to go up a ramp would be much nicer.
Having to double tap and hold the jump key to float would be vastly improved if you just had to hold down the jump to float.
Sometimes it was hard to see the difference between a wooden wall and floor. Adding in some AO would likely help that issue.
Keep it up!