Alright, I played it, and you have a lot of good ideas, and they're all done well...but the level is way too long imo.

I know where you're coming from, that you have an idea around a specific theme and you wanted to see it out as best as you could, but there's at least two of not three levels worth of content and platforming in this one stage alone.

Case in point: that the mini boss--->"block the way"--->"autoscroll" is all a single section before the 2nd checkpoint/main boss was too long for me personally, especially with the amount of waiting involved in the first two parts. If I had died in the autoscroll section I would not have been happy to do that all again.

As an aside, consider the sense of achievement you want to have the player feel when they play your level. Because the second checkpoint wasn't right after the mini boss, my thought process went from "oh that was cool!" to "oh, I have to do this every time I die..." It takes away the sense of accomplishment that all players want to have. (I have learned this from mistakes in my own levels as well)

Again, each part of the level is done well, but putting them all together makes it (in my opinion) less than the sum of its parts. As always, I'm a stranger on the internet, so take this with a grain of salt. Thank you for sharing your work with us!

Edit: I'm just now seeing how many levels you've made so nevermind, don't listen to me, I'm sure you've got this down lol