So, the Seonwoo who built the clinic was always from the real world. He got transported there at the age of 9. And he finally went back to his world in chapter 61. While the game world Seonwoo we having been following from chapter 1 always belonged in that hunter like game world. But got to enjoy some time off in the real world before having to return back to his game world. Our Seonwoo was always the NPC of his hunter like game world. But he thinks he is from the real world. Which isn't the case. Like bish you were vacationing in the real world. That was never your world.

Basically the version of the MC we followed from chap. 1 was never from the normal world. He was from the game world but swapped places with the other version of himself so young (nine years old) that he didn’t remember. However, the version he swapped with didn’t forget that he came from the normal world, and built the clinic we see at the start of the web series to cope.
When they swapped at the beginning of the series they were actually returning to their PROPER timelines. So our MC returned to the hunter timeline and the version of the MC in chap. 61 returns to the normal world.
It’s confusing but I don’t think this is a continuation of the previous version of the MC we followed, it’s actually the other side of the story. We r seeing the version of himself that he replaced (the one who made the clinic in the game world) and what he did upon swapping places. So this is BEFORE the MC dies I presume. Taking place at the same time as Chap. 1. Hope this makes sense.
(づ ̄ ³ ̄)づ