Your argument was that basically that because many species are promiscuous, one selected one (humans) must therefore also be promiscuous. This is not a logical conclusion, as you said yourself that there are apparently differences in promiscuity in nature ("most" does not equal "all"). In other words, you would first have to figure out why certain species are more or less promiscuous in order to establish whether it likely (or not) applies to humans.
If nature was based on majority rule, we all would still be bacteria and just reproduce asexually.
Likewise, you cannot dismiss whether our society makes promiscuity more or less likely, as you have not established conditions that are associated with promiscuity that we could discuss.
I am going make an analogous argument to yours to demonstrate why your original argument does not hold water:
Most animals are arthropods (well above 80%). Therefore animals are evolutionary primed to live like insects.
What we can discuss, which is somewhat outside biology is about human society and how that influences partner structure. But again, doing sweeping positive correlations and then somehow invoke evolution is just bad science (and which is why evolutionary psychology as a discipline is in deep trouble).
But even using somewhat shaky arguments in that area, it is very weird that you focus on female promiscuity. Assuming big fitness arguments (and again, research has shown that it is actually far more complex than these simple narratives), in most mammals, including humans, males benefit more from being promiscuous than females. The reason is fairly intuitive, because a) in most species females invest more into the offspring and b) extra-pair copulation for the female does not automatically result in more offspring as for males.
Now, this view has been challenged to various degrees, mostly using insect models, again highlighting my above argument, if you will. In observational studies In birds, reproductive success seem to increase for both, male and female partners in a number of partners. However, the advantage for males is still more obvious than females (and the latter is trickier to study).
If we focus on humans, there is of course the issue of social norms- in many societies it is more permissive for men to be promiscuous than women. As such, it is not surprising that most surveys indicate higher promiscuity in men, but this again is challenged with changing gender roles. So again, another societal, rather than evolutionary factor.
I suspect that what you tried to say that serial monogamy is in polygyny (succession of female partners, as the reverse does not make sense) but why not polyandry?
This is not to say that the area of research is not fascinating, but I think the way you start off is far too narrow and biased toward a certain narrative that it actually runs counter to existing research.
To kick off such a discussion with a focus on human species you may want to look at a few accessible papers such as Schacht and Kramer (Front. Ecol. Evol. 2019) for a general review. The paper does actually discuss (and refutes) some of the common popsci narratives.