" And the LORD God said, It is not good that the man should be alone; I will make him an help meet for him.
 And out of the ground the LORD God formed every beast of the field, and every fowl of the air; and brought them unto Adam to see what he would call them: and whatsoever Adam called every living creature, that was the name thereof.
 And Adam gave names to all cattle, and to the fowl of the air, and to every beast of the field; but for Adam there was not found an help meet for him."
I am not sure what to do about the "out of the ground" phrase - perhaps the aboleth bio-factories I mentioned also seeded the land with animal life? However, this "naming of every beast" business strikes me a lot like a grand biological survey of all life forms on the planet. The aboleth presumably didn't have to survey the planet since they created all the life forms in the first place (unless they stuck around for long enough that evolution became a serious factor). So let's make the survey the work of a later civilization - in particular, the mythical Oreanor which is also called the First City. As they were masters of magical biotechnology, searching the world for life that might be useful for their research seems appropriate. Perhaps there are still some hidden repositories with samples somewhere in the world... such as in the Cold Frontier, where the First City certainly had active outposts.
" And the LORD God caused a deep sleep to fall upon Adam, and he slept: and he took one of his ribs, and closed up the flesh instead thereof;
 And the rib, which the LORD God had taken from man, made he a woman, and brought her unto the man.
 And Adam said, This is now bone of my bones, and flesh of my flesh: she shall be called Woman, because she was taken out of Man."
When I read that women were designed later - and as "help meets" to boot - I am immediately reminded that the First City basically created all the nonhuman races with their bio-magics as helpers (except for the elves, who were an experiment in genetic transhumanism). But it would be fun if a garbled account of this process survived somewhere in mythology. But garbled to what degree, and in whose deity's mythology?
Let's pick the deity Ouneiros, who is basically a demigod worshiped only in the ancient city-state of Ouneirotur in the Lake of Dreams region - which just happens to be the same city that the First City was allegedly in (though nobody has identified its precise location). Let's go with this idea:
Ouneiros was also the patron deity of the First City (or so he claims). And after the people of the First City "took stock" of all the animals in the world, they begged him for helpers that could help them in a way that the beasts could not. So Ouneiros took various body parts from various human inhabitants of the city and turned them into various nonhumans:
- Elves (role as "companions"): Hair from the fairest maiden.
- Halflings (role as "domestic servants"): A foot from the most good-natured household slave.
- Gnome (role as "artisants"): An eye from the best artist.
- Dwarf (role as "laborer"): Testicles from the most hard-working worker.
At least, this is what his Book of the First City claims - one of the few texts describing Oreanor, which is why it is of so much interest to scholars, despite its often dubious contents. Ouneiros rules his city still, as he has done for millenia, and the city remains unchanging. Elves, halflings, gnomes, and dwarves are the only nonhuman races allowed to exist in the city, and they fulfill their ancient roles as servants - though since many of them object to this subservient role and flee, slavers occasionally capture members of these races from elsewhere and sell them here.
" Therefore shall a man leave his father and his mother, and shall cleave unto his wife: and they shall be one flesh.
 And they were both naked, the man and his wife, and were not ashamed."
My key phrase here is "shall be one flesh". Perhaps the First City also dabbled in combining men and women into hybrid critters? Whether this is something as simple as a hermaphrodite or as complex as an artificial intelligence formed out of multiple brains, Ouneiros probably disapproved either way. Though the latter are probably more interesting if the PCs encounter them in a long-abandoned First City lab...