
If Guwon really isn’t human, maybe it’s connected to the title. The second time the King defies the gods and evades his punishment or “death”, he returned to the mortal world to live out the remainder of his life. The first time he trapped Thanatos and as a result no one could pass over (similar to what we see here with the living dead.) His failure to see fault and repeat his mistake a second time was when he really pissed off the gods and received the boulder rolling decree. Maybe Guwon doesn’t have his memory because he defied death on a deeper level than the regular humans surviving the apocalypse and he’ll be receiving/has already received a cross to bear to resolve the apocalypse or protect what he cares about.