There's a lot to like here. The music is good and sits well in the background while leeting you focus on exploration. The animations are so good at times they almost feel rotoscoped a la prince of Persia. My one note on aesthetics is to not make enemies that look too similar to the player - the first time I saw a fellow pirate that seemed to be wearing similar garb I thought that this might be a friend. I ran up to him. He shot me. I felt betrayed.
I think people have already talked about the character controller. Honestly, slopes are a pain to get right in platformers in general and I'd nearly recommend not doing them in a jam unless you have a tight controller ready to go already. Momentum can really get out of control. Not sure if coyote time is here. Would recommend if it's not, would increase coyote time if it is.
The level design here is pretty good. I felt like I had a clear mental map in my head of the various ability related locks as I passed through the world, and knew where to backtrack to when I needed. There aren't too many routes to take at first which really helpes the player get a sense of the world, and doesn't make backtracking too tedious.
The parrot ability is very interesting and I think you could do a lot with it if you expanded it further. You might want to think about what happens to the player while the ability is in use. Is he still gonna be vulnerable while the parrot is flying, forcing you to find a safe spot? Does he become something invulnerable while it's in use? Right now, momentum remains for the player while using the parrot so you might want to turn this off. Could be obstacles for the parrot while trying to get to a switch - such as moving spikes etc. Lot of fun to be made of this.
Anyway, thanks for the game and hope you had fun developing!