I am immediately captured by that art style, I'm in love!
I actually like the 2.5D style you're going with this. The animation, character, enemy, and world is so bright and nice. However I'm going to comment on the usage of pipes: I would recommend to find a better alternative for zone warp/shooter so it's not too straight in the face on what you're referencing :9
Other than that, the level design can do some adjusting: try to not put too much things into the screen at once, give them a bit of space in between things so player can proccess what's going on and where to go. Reduce the idea of "pick a pipe" and encourage the idea of exploring without getting punished(getting nothing). Also try to create a clear checkpoint rather than make player wondering if they have passed a new safe place or not.
Also try to avoid camera that hides path like this unless it's a secret and given a hint by environment shape that there's an actual path there.
Other than that, really nice work! I also love the title choice and overall vibes, really takes you back into a real classic.