I'm grateful you incorporated keyboard controls for desktop. It matches the flow I'd feel on mobile, I think.
The UI is easy to understand, but I wish it were easier to tell which levels I already did. I was wondering for a while why level 7 was locked, only to later realize I didn't do level 6 yet.
I understand that the game is meant to be taken slow, but I enjoyed going fast and kept feeling an impulse to do so. Bumping into crabs was way more fun than trying to avoid them. At some point, with so many obstacles and all the waiting I needed to do, the game went from fun to exhausting. I ended up with 15 stars, and didn't feel like getting the other 15 to unlock the last level.
Have you considered adding a timer and making this more of a time attack kind of a game? My instinct tells me it's an angle worth exploring.