They're Savefiles, engrams, Digitized memory. No longer in standard "Living Being" Format. Can't be Transplanted in Conventional Bodies. Let alone Like Otis.

Move on, Let Go.
Just as the game tells you.

The Memories Could only Update at Most.

They have no bodies, and they require Soul Energy From the Living.

They'll Kill for what is already Dead.

Unlike SoulKiller and Mikoshi. There is no going back once you're this kind of dead.