Hi,
Nice, I think you can be proud of this entry. There are some low hanging fruit for improvements I would suggest.
I got confused in the first level, I had collected the stars, but hadn't connected the dots that the ballon in the beginning was the end. So I randomly ran around until I noticed it had lowered. Some visual that it lowers or keeping the first few levels with the goal all the way to the right, could help.
The mouse rotates the camera =)
It can be hard to land the jumps. Maybe a little air movement (25-50 % of normal) would do a lot. Also try looking at how other platform games actually cheat, with coyote time.
Looking forward to seeing you/your games in a different game jam or maybe next year =)