Thanks for playing!! I really appreciate it. I'm kinda surprised I was able to make something that solid, so that's good to hear.
The secret levels are basically what you unlock with the trophies. If you get all the trophies in a world, you unlock one, and all of them are loosely based on the original game's level layouts.
As far as all the stuff you mentioned, I can definitely fix those. I just changed the wall jump so you dismount if you let go of the wall, though there's a small buffer so it doesn't feel finnicky. I'm not sure how I'll fix the large enemy hitbox thing but I think I have a few decent ideas, because I got stuck a few times too. I'll just need to figure out how to properly push you out of the hitbox.