You made this in a month?! That's amazing!
Lots of gameplay for a game jam submission. I wish I had the time to finish it.
It seemed like finding all the things on each section is optional. Is it? I recommend some kind of indicator of where the exit is once everything is found.
Once I died, I quit because I had to start all over, even go through the tutorial prompts and dialog. I wasn't expecting so much to play through.
I loved the double jump and ledge grabbing but I feel like the player should float a bit more and not immediately drop after the peak of the jump. There's probably a ton of tutorials on improving movement in platformers.
Otherwise, the execution was great. Lots of enemy types. Either it was a coincidence that I received health items when I was low on health, or health drops were rare. I had a good time.