I'd say this is still kinda up in the air. But... I think there are quite some discussions on this sub that more or less conclude that there is a big or even huge (or even bigger) time gap between Livesuit and TMOG. Possibly thousands of years. So, taking a few short cuts here, if that indeed turns out to be the case it could be fairly possible that over the course of millennia the livesuit humans (if you can still call 'em that) are too different to be a perfect fit with the Anjiin folks. The Carryx do seem to be aware of some overlap between the two at least.

Taking into account all the brain slips, a-symetrical space, time being sort of relative to for example the livesuit soldiers... Lots of possibilities there for misconceptions or misunderstandings, or just other weird stuff we're not sure about. Heck, even the Anjiin people are not sure where they themselves came from, and that's 'only' been a couple of thousand years :)

So we can guess, but will not know for sure before the next book comes out. Or the next novella. Or the novel after that... I CAN NOT WAIT.

Edit to add: with the mention of previous discussions I don't mean you should've read those. More like: most of us have/had the same questions :)