This is cute, and does a great of establishing mood.
I felt like the game didn't lead me to discover that I could double jump. The respawn point in the room where a double jump is required to progress is below the platform, and ends up putting the player into a death loop, which made it doubly hard to discover.
I wasn't able to get through the door on top of some shelves above a chair, so if there's more game past that, I didn't see it. What was there felt like a good start, though, and I particularly enjoyed the slightly off tilting.
Because the AppImage was uploaded as a loose file, executable permissions can't be preserved when downloading, but if you pop it in a zip file, they will.
Good luck with the project if you continue development!