Alright, so, this demo seems like it has great potential to result in an awesome game.
The visuals are great overall and I also really liked the artwork during the intro. Speaking of the intro, it ended really abruptly, but this is a demo made for a game jam, so it's understandable. Just make sure that the transition from the intro to the actual game is better in the finished product.
The dialogue seems pretty good, good job there. The characters feel like actual people.
One thing to note is that the beginning seems to be way to slow-paced. There needs to be something that grabs the attention of the players, hooks them in. Like this it's way too much of a slow burn and less patient player will probably give up before they reach anything interesting.
It also seemed like it's a bit too hard to tell what to do next. If the demo has an ending, I didn't reach it. I found the door to the wing of the school that's apparently under renovation but didn't seem to find a way to progress past that. And I seemed to wander aimlessly a lot of the time.
So, definitely revamp the beginning part of the game later on somewhat, it's the most important part of the game to get right.
One question, you've mentioned that you had to cut out a lot of features in order to finish this demo before the end of the submission period. Did you plan to include any of the bonus challenges from the game jam but didn't have the time to do so? It doesn't matter either way, I'm just curious.
Anyway, keep working on this. A finished version of this could be truly great!