The idea is great, the levels are well made, except for the level 3 and 4, I could say they should be imrpoved; and the boss looks really cool, LOOKS, because it's very difficult and I look at some parts thet were just imposibble if you haven't played until that part, many levels were just difficult because the hit-box, the music I liked most, the last one for the boss is just wonderful, but there are many details you should check out.
1- Check the bases hit-box, I hit some ones even if the base was flat (I talk in special with boxes objects and the vertical bases)
2- Hit-boxes, little less biggers
3- Level design, by making it fun more than just difficult
4- Give an alert when is gonna attack the boss, what is gonna happen next, and give time to react to the attacks

P.D. Thanks for the tip ctrl + mouse wheel, I didn't know it until now c;

As a Unity developer myself, I have a few tips to make this game better.

1: If you want the music to not start from the beginning when you change scenes, use DontDestroyOnLoad().
2: I advise using physics based movement instead of changing the transform position for better feeling movement.
3:Use custom UI buttons

Pretty good concept though, this game has potential.

I like what there is so far, but I feel like the wall-jump controls are kinda clunky, I'm struggling to get onto the next wall quickly and I would get stuck on the wall that has a gap in it. I'd also appreciate the game window just being smaller and not having to resize my browser.

Maybe you could find a good pixel font for the instructions, and have the game music not restart when I die? It's these little things that can really make the aesthetic of the game feel complete.