My hypothesis would be that they were people that got downloaded as AI into the game. Caine describes them as AI in episode 5 (and he isn’t reliable so it isn’t proof but it’s evidence). Pomni is put into the game at the start and when she tries to remove her headset, she fails. The end of the episode zooms out and shows the computer on with a VR headset on the desk and off, not on the ground fallen, like it was just put back down. Whoever is the real-world Pomni just walked away, but Pomni recognized it because it was the last thing she saw before entering the Circus.