What happened to the humans in Arcpunk, and why do they exist only as massive statues?
Humans never inhabited the Chunks of Arcpunks cosmos. They exist solely as mythical beings in stories and legends.
However, according to lore, the cosmos (that is, the entire plain of reality of Arcpunk) went through several iterations, each of which was newly created or conceived by Gotikodohaleto, and later by Gogosos-Tosakurru.
Some believe that the few human statues are fragments from earlier iterations of the cosmos, which manifested in their present form during the creation of the current version of the Cosmos. There is no proof of this, of course - but the existence of other artifacts and fragments from earlier iterations suggests that such a concept is at least within the realm of possibility. Furthermore, there is no indication that these rather large statues were ever shaped or carved; instead, they appear as though cast from stone in a single process.
The myth of the humans in Arcpunk, and why some believe the statues are relics from earlier iterations:
Humans appear in Arcpunk purely as mythical beings and are part of a kind of origin story for the cosmos. These legends tell of at least two iterations that existed before the current one, and in one of them - the first - it is said that humans truly existed. They were called the Kruswa.
The Kruswa:
The Kruswa were the children of Mushma, who herself was the daughter of Ort, whose mother Soma’sona was the first being ever conceived by Gotikodohaleto (the Dreamer), thus opening the first cosmos. There are many stories and legends about the time between the opening and closing of this first cosmos, but what matters for the question above is that the Kruswa played a central role during this time.
However, a serious incident occurred. A king of the Kruswa claimed time itself for himself. He did this to escape his judges, since his reign had only been a kind of probationary period—which he had completely wasted.
As a result, an entity was created to stop him. But something went wrong, and not only the king, but the entire cosmos was at risk of being consumed by this entity. This was the reason Gotikodohaleto had to close the first iteration of the cosmos.
But not everything was lost. Urm, the brother of Ort, saved some of the Kruswa and was himself saved by Gotikodohaleto and transformed into Eplin and sacrificed himself to become a new home for what had once been the Kruswa. However, during the transition into the new iteration of the Cosmos, the Kruswa changed significantly, marking the end of the age of humans.
Whether there is any truth to this story, or whether it is merely one of the P'kun’s fantastical tales, remains unclear. However, the very existence of the statues - as well as many other relics scattered throughout the cosmos - suggests that some of these events might indeed have happened.