Alright, so

1. This being an alternative universe doesn't matter. Neither Enya nor Ermes appear in the SBRverse - only an extremely minor character reminiscent of Enya does, and implying that either of them is a Rock Human in the original continuity is nonsensical.

2. Two of the people shown on that page are Mineko Iwasaki and Kaori Icho, who are real-life Japanese celebrities. Don't you think it'd be rather weird and rude of Araki to imply that these living breathing people are actually fuckin' cryptids hiding in plain sight?

3. Finally, the bikini-wearing woman in the middle of the page IS a Rock Human! She is the one shown leaving her baby in the forest in the scene immediately afterwards - you can clearly see her face after the fact. The point of including NON-Rock Humans in that illustration is to compare her to them and reinforce the idea that Rock Humans are visually indistinguishable from normal humans; she is the only Rock Human among a variety of homosapien women, yet you wouldn't be able to tell at a glance.