Trying to connect some scattered clues in the chapters so far, I'm guessing Jeongtae is very dangerous.
I think these hunters are trying to complete a transition back to humanity by collecting souls, and once they catch a certain number, they're able to cobble together a human personality and appearance, and then blend into our world.
Seeing as a hunter in a previous chapter, upon being defeated, lamented that it had been "so close"; as another one addressed Jeongtae as its (his?) son past chapter; and as Jeongtae hesitated to answer how he knew so much: I'm guessing he is a former inhabitant of the future world who successfully hunted enough souls to become a normal human. I can think of no other way he'd know so much from just observing, anyway.
So the question is: what's he trying to accomplish by dangling the "hero" bait before Min-ho, who seems to have inadvertently found an effective way of killing hunters? The best-case scenario is that "Jeongtae" is on the side of present-day humans, as in kicking down the ladder he used to climb up. But I wouldn't bet on such a benign motivation.
On top of that, it seems that there's something more to Yun-yeong as well. Can't wait to understand it better.
The future world thing is a weird path for the story to take, we'll see how it goes
Well, the future world thing is something I had considered before but didn't take seriously. The way everything is in ruins seems very much like a post-apocalyptic version of our world. That could just be standard spirit/dark dimension shit, or it could be an alternate timeline but the same date or a future point in our timeline.
Spirit dimension was the most likely, but in these cases you always have to wonder why things in that world are damaged the exact way they are. It's supposed to be a mirror of our world, but how does damage accumulate in the mirrored version? It doesn't make sense. There are ways to make it make sense, but not intuitive ones. The last time I had this issue was with Stranger Things, and I was right: the Upside-Down was not a mirror but a clone, copied once when contact was first made, and then degrading from then on (of course, the dimension itself already existed, but was influenced to be filled with a copy of our world).
If he's right that it's a future, I think it's clear that something went horribly wrong, something supernatural. These things didn't evolve from us, they probably aren't breeding. They are more like the twisted remains of what's left of humanity. The future world doesn't have any normal life, the trees have no leaves, there are no animals seen. Nature would have taken over the cities again if nature still existed, but it hasn't. The ability to see souls and sense fear and shit are not evolved abilities. These things are closer to demons.
If he's right, the spacetime overlap was probably an intentional occurrence by... something.