This game is so visually pleasing, and the music is very fitting. Sound design is on point as well. I loved the changes between the first scenario and the second, and the fact that the same ziplines that were so colorful at the beginning of the game looked like spider webs in the cave (at the point I got to the boss I was 100% certain on what it would be haha)
I found a bug while fighting the boss for the first time, all ziplines stopped working (I think I died right when it disabled the ziplines after hitting it, keeping them all disabled forever), however I got to the end of the game on my second playthrough. Oh, and the boss reminded me so much of the Donkey Kong bosses, including the camera movement, that was pretty cool.
I enjoyed the challenge of getting the HP UPs, it really added to the game.
My only issues were the platforming (especially while getting used to it at the beginning) and the combat, but nothing too problematic. As other people said, coyote jumping would probably help a lot. My grip with combat is that it seemed I had to be very very careful when getting up close and personal with the enemies, and some of them were waaaay too vicious IMO (lol I'm looking at you, bat). Also, I think the first one should be squishier, maybe die in a hit or two.
I personally think you did a stellar job with this one, the game is full of personality and creativity. I'd also love to see a game like this finished and polished.