Earlier quoted context omitted.
Antihumanism is an edifice wrought of unsubstantiated assertions, self-contradictions and wilful ignorance of evidence.
Of course it is, which disregards a good deal of research in cultural studies accumulating over the past half of a century. But you know that, as you clearly have studied the field.
Human beings are animals, and thus the product of evolution. We are not blank slates, but highly specialised machines with innate tendencies and potentials. Almost anyone could, with minimal difficulty, list any number of phenomena universal to any human society: pain (and aversion thereto), communication, laughter, anger, etc. It is avowedly extremely difficult to separate ourselves from our inculcated norms when reasoning about human nature, but that does not refute its existence.
Of course, suggesting that human beings have no natural tendencies evolved for their survival ignores an overwhelming preponderance of evidence accumulated by biologists over the past century. But you know that, having clearly studied the field.