Thanks for the criticisms. Ultimately I spent a little too much on backend coding and too little on the actual level design which would probably attribute to your first point. I had a few more ideas on puzzles using the checkpoints that in the end didn't get time to work on/put in. I was also wary of not wanting to make it too hard as it's a jam as well.
Definitely want to see what further I can do with this backend though - I won't be continuing this game directly but interested to see if I could come up with a good prototype for a platformer level. I'll keep in mind you point on the acceleration going forward.