Responses
Me when I have to bullshit my way through a test I didn't study for:
Nah, just kidding, you're actually cooking up a solid theory though, unfortunately I don't think the author is clever enough to have come up with something like that, they just have a terrible case of same-face syndrome tbh.
We are seeing things from MC's perspective.
Remember he was a twin, but when we saw his brother, his brother in MC's memories did not have a face. I think everyone having the same face is a manifestation of MC's guilt that he has towards his brother.
Either you don't have a face or he's looking at his own face (ie his brother's).