For a first level it isn't that great. So many ridiculously odd level design choices that I really want to know the backstory of. The textures are repetitive and blend in with each other, i don't think some of the spring sections have been tested much. Theres random stuff that makes 0 sense in the level. The visuals also aren't that great. It's rather short and has the classic Final Demo style canyon carving cramped design.
This is pretty good for your first level! I like the synergy that the textures and the music creates, it builds a real sense of intrigue.
A few pieces of criticism to address for a future update if you decide:
Finding the way forward is very difficult at some points, there's a small hole which appears like a death pit which is the way forward.
The scale at the beginning of the level is perfect for the player to run through comfortably, but once we reach the cave, the level becomes so cramped I can't even move my camera properly. You definitely want to scale that cave up 4x or more to be more comfortable to traverse.
You should, when you get the chance, change the NextLevel in the Level Header to NextLevel = TITLE. This will mark the save file as complete, instead of transitioning into Greenflower Act 2 (which is pretty silly when you think about it).
Otherwise, this doesn't break the rules and everything checks out. Welcome to Releases!