The concept is solid and the results are incredibly impressive for just forty eight hours. Everything is mostly intuitive. And I could very easily see a more refined version of this level built into a fuller game. Short burst levels with an end level boss, it's all great stuff!
If I could make a few notes:
1. There needs to be more recovery time each time the player is hit. Once they take damage, there should be a second or two when they're invincible because otherwise you can go from 3 bars to 0 in a second.
2. The boss fight glitches often. Either the path will be blocked off and you'll be stuck standing on mid air or if you reach the second phase and die, when you respawn at the checkpoint, he's already in the second phase which makes it impossible to even enter the boss arena without taking damage.
3. There isn't enough grace period between the boss' attacks in his second phase where it feels manageable to dive through his attacks.
Really nice work in such a remarkable turnaround time!