I like this game, it's fun. The movement felt almost great. Physics is challenging but not impossible. The level design is pretty good- it never felt repetitive, boring, or unfair. I like the feedback on the checkpoints- it really gets that "yay" feeling without breaking immersion. The way Banana "wiggles" as it spins really adds a lot to the gameplay experience (because Banana does not feel "boring" to look at).
A few things that come to mind are-
1. When I played for the first time, I pressed D to go "right" as it felt more intuitive (because of the camera angle) but Banana flipped off the platform, leaving me confused. But when I realised that I needed to press W, I adapted quickly. (But I did press A, D out of instinct more than once in latter sessions.)
[If you decide to stick to the present control scheme, you could rotate the instructions at the start of the level so that the W would be rotated to the right side, in the appropriate direction., while A and D will be to the left and right like on the keyboard. This will convey which side the player will move on pressing which key. (personally, I recommend changing the control scheme to make it go right on pressing D )]
2. Visual depth needs to be better comprehensible. More often than not, the shadow is not very visible and I would slip off a platform because I did not realise that Banana was at the edge of a platform.
3. You may also want to reduce the overall brightness just a little bit. It may not matter too much for a short game, but if you decide to add more levels, it may be beneficial to reduce the strain on the eyes for longer.
Overall, it is a really nice game with cute and comical essence. Great work!
Go Banana!