Good theory. The Apex faces being shown as post-mutation always makes timelines hard to determine, but maybe the Cultivator told the Ancients about it early for some reason.

the apex didn't exist either? it's very obviously a prophecy

this mod, makes SO MUCH SENSE

correction: the eyeball sprite isn't just from the Ancient Essence Chest, but rather it was seen on a teaser image from the gate before it was implemented. Since they removed it, I'd argue it could be another face, but the eyeball is still more likely

Considering that it's heavily implied that the Novakid are the fragments of the cultivator that gained sentience, their face being on the gates never bothered me. It may have very well been the Cultivator's face itself. Also, I doubt that the Ancients are truly extinct, I personally think that the Mysterious Trader is a surviving member of them, how else did he get the keys to the Vaults.
As for the missing face, I assume that it's the face of the Ancients themselves. They do sound quite pessimistic in their mural in the Ancient Vaults, so I can believe that they'd remove their face from the gates.
There is also the theory that the Ruin or the unidentified fossil's race was supposed to be the 8th slot, I assume they left it empty to get people theorizing. For example, the eyeball sprite on the Ancient Essence Chest fits into the slot perfectly, implying that that might be the Ancient's face.

The empty slot represents the Ancients, having disappeared without a trace.

This annoys me every time I pass the gate. Thank you for this important fix to my sanity.

@warmainiac The yes is to wether or not you wondered about it, but that's not very clear I guess.

the last question does not seem to be a yes or no

Novakidding

@evanaug fair enough, to each their own

@Armok It's never stated how long it took after the Cultivator's death for the Novakid to start showing up. The Ancients may have died out several thousand millennia before the Novakid even began to emerge from the stars. There's probably a good explanation as to why the Gates were given extra slots and Novakid, but I haven't found it yet (Other than the devs not thinking though what they were doing).

As I interpret it, the Nova Kids are actually fragments of the Cultivator considering it says that its fragments took on a life of their own and exist wild and free. Which that descriptions sounds A LOT like them. So... yeah, they really shouldn't be on that gate unless it was constructed after the Cultivator fought the Ruin but before the Ancients disappeared.

or if you're me you can just assume that the ancients didn't just instantly vanish and spent their dwindling years carving novakid heads and removing the 8th one

but hey, to each their own :P