Sure thing.
1. For the end of the levels if all keys aren't collected, after the message, if I didn't walk backwards, I could push passed the message and fall off the map. Maybe just put a gate or something that the player cant walk passed, but with all the keys when they collide with it, it goes to the next zone?
1.5. Similar issue, maybe just make boss arenas closed off when they start, as I was able to do the same within the first demon fight in the graveyard.
2. The dialogue system just felt a little off having to go back to my mouse to make choices (unless I missed something), maybe implement something that could allow the player to use the dialogue system with arrow keys and space. Not a big deal, just fluency, but it is a little nit picky so I wouldn't worry about that too much.
3. In the final level, the camera zooms in a lot and feels like a huge shift from the previous levels. I think a little is fine for the feel you're going for, but there were times I couldn't see the platforms below so I thought I'd just die or had a hard time navigating. Maybe just a little less zoom to show a little more of the ground.
Those were the main ones I thought, for where you're at, I truly believe you'll just learn/grow skills throughout future classes/personal projects. Was rad, excited to see more work from you! :)