Thank you for your detailed feedback! I had to fly out a couple days before the end of the jam so the ending was rather sudden.
Unfortunately my monitor seems to display colors a lot brighter then they are which led to me thinking that they would be correct. When I played the game on another device, it looked way too dark to play! That will need to be changed.
I agree with the level design part - it was my first shot making a somewhat larger world and while I do think there is a sense of scale conveyed, a few parts of the world just feel empty.
Those were boots! After playing through, they don't seem to destroy themselves when they are obtained. But they give the player a permanent speed boost.