Well ... I suspect they had the essentials down pat.
It has been my experience that the farm boys and girls of any culture have a pretty good idea what's going on. Gummy mentioned to me problems with Arabs of the city variety and sex. But I bet the Bedouins don't have those problems.
Surely the people of the bible didn't know modern biology, but as PH says, the basics were probably well understood. And I think they realized that if you had a nose like a macaw, you'd likely visit that affliction on at least some of your children.
The mechanical, or to be more precise, the "hydraulic" part of it, at least. If they didn't, we would be here today to comment on it.
<< Nobody in Biblical times had the slightest clue as to how human reproduction worked. >>
<< Well ... I suspect they had the essentials down pat. >>
They certainly knew that sexual intercourse could result in pregnancy -- and they knew that the ejaculate form the male had something to do with impregnating the female. But beyond that -- zip.
There is the biblical story about Onan. His brother had died, and he was required by law to marry his widowed sister-in-law and impregnate her, so she could produce offspring as heirs of her dead husband. But Onan "pulled out" and "spilled his seed on the ground," thus incurring condemnation.
This shows they knew that the male seed impregnated the female. But no one knew more than that till recent centuries.