You can't even prove other _people_ aren't "faking" it. To claim that it serves no functional purpose or that it isn't present because we didn't intentionally design for it is absurd. We very clearly don't know either of those things.

That said, I'm willing to assume that rocks (for example) aren't conscious. And current LLMs seem to me to (admittedly entirely subjectively) be conceptually closer to rocks than to biological brains.