maybe its a vampire, but the wall of Plato's Cave counts as a mirror?

Because projection. Man reversed the order of that saying.

Alternatively, it could be figurative. We are all kinda egotistical assholes?

Original

To be fair, you can make a sim in your own image without them being able to see you. Maybe we're all just sims

Or like this:

Isn't this from Casper?

"Arrivederci America"