Maybe they combined religious and prurient motivations in those days…
(I.e. “Oh god, oh god, ooooh god…OOOOOH GOD!”)
Unfortunately, unless we find a cave painting, we’ll never know. Some backwoods european cultures not totally infiltrated by church mores had some very interestingly different attitudes to sexal activity; as did other continents.
One suggestion I read was that the “worship” or idolization of the female form was supplanted by “male gods” possibly as populaton became numerous enough that warrior protection was needed, as agriculture became prominent and homelands needed defending, or perhaps as men discovered the role of sex and paternity (possibly when they took up animal husbandry?).
We beat to death the question of “when did people figure out sex = babies?”. The follow-on to that is the man now had a valid reason to keep other men away from “his” woman.
The trouble with that thesis is that jealousy is too ingrained an instinct to be a sudden discovery 10,000 years ago. And some cultures do have more lax rules or perhaps celebrations (I read once that middle ages Octoberfest, for example, was a pretty raunch time before the Reformation).
So it’s possible that humans simply kept two contradictory ideas in their heads simultaneously - the male protecting his “harem” and the worship of the “you’re a lotta woman, baby” ideal… and made staues of the latter to get in the mood for fun and contemplation. After all, to worship to warrior man ideal, all they had to do is look at their own spear, they didn’t need to make any extra statuettes - except the example in the link.