Interesting game! The different ducks made the gameplay more unique (my favorite one was the wizard ducky). I think some SFX and music would've made the experience more enjoyable (I end up composing a lot, so personally the lack of sounds impacts me a lot haha), but I understand that because of time restraints, it wasn't doable. I'm hoping you'll be able to implement that in your next game!
I do think jumping is a bit slow (or rather, the jumps are really high and can make the platforming feel slower), and reading the comments, I understood that it was intended to be that way since some jumps had to be longer than some other ones. I think one way you could've adjusted to this was with a double jump because that way the player can jump once for shorter jumps, and do a double jump for the longer ones.
Overall, not a bad entry at all! You got a good game concept going on here. Wishing you the best for your next entries/games :D