The old Necron Codex called them The Talismans of Vaul- Vaul being the Eldar god of the forge.

In the Eye of Terror campaign, Eldar is sucked into the Corrupted infinity circuit of one of them.

Suggesting some Eldarish nature to them.

I did wonder if this might be retconned- with it instead being a tesseract labyrinth, and with the Blackstones being used by the Necrons to shatter the C'tan.

On humans- while when the Old Ones were beaten, and the Necrons went into stasis, 60 million years ago, the humans were only shrewish-looking proto primates, the Old Necron codex said the Pariah gene in humans was the result of "a terrible crop planted in ages past" by "the Devoured Ones"- seems like a hint at Necron meddling.

Maybe with the new codex saying the Triarch Praetorians were awake all that time, it now makes more sense that they were the ones meddling with humans, much later on.