This makes so much sense now. That's why he was afraid of the boulder rolling down and crushing the town..
I think you're on to something! He's been alive for thousands of years pushing a boulder the size of the moon up a super steep hill. During all that time I'm sure he completely forgot the life he had as a mortal, and some incident has caused another "no death" situation like when he chained Thanatos the Grim Reaper to the rock in the legend.
Something I see questioned routinely in the comments are his tattoos. I don't know if they're tattoos so much as they are the remnants of scars. There's one on his neck and one on his foot (not to mention the black tats on his arms). Maybe he tried cutting off his foot to get out of the punishment, and when that didn't work he tried cutting off his own head? As an immortal they would probably just reattach themselves but also a scar, which is why a lot of ppl think he is a Frankenstein monster.
I 100% believe he's not a monster, but Sisyphus risen from the underworld. Although it does sound like Sisyphus was a pretty big asshole when he was a king, he's not a monster now (that we know of yet). I'm always excited to see what happens next, and I'm REALLY excited to see what happens when they get their memories back!
WAIT HE SAID THAT? LOLL I HAVE TO REREAD
THIS ATE WHAT
OMG! What you said about him trying to cut ofd his foot and head so that he could stop being an undead! CHILLS!
it is said in the greek mythology that sisyphus was cursed of immortality due to his sin of thinking that he was better than a god, which in this story might explain why he can be considered not as a zombie but simply undead? and perhaps have been alive for thousands of years?
or that one curse Hades placed on him in which he is to roll a boulder up the hill only to watch it roll back down over and over, perhaps this might signify reincarnation or time traveling in this story, for Guwon I mean- but idk I might just be overthinking it