A bober game, amazing! :D
[insert that Polish meme]
Jumping is a bit too "sharp". A common trick is to lower gravity while the jump key is pressed to allow for different jump heights depending on how long a jump input is held (yes, this is unphysical, but very intuitive for gameplay). And the gravity is perhaps a bit too strong and could use some way to limit the falling speed (either by implementing a cutoff or friction). For swimming, jump input could be used alongside up input to swim up, for more intuitive controls.
Lovely graphics, well polished look. Super cute! And I saved the pond! :)