I ran into that “thought process” at University. A professor claimed that all cultures are equal, and none are any better than any other. With the horrific blood-letting that more or less defines the 20th century in mind, I pointed that it follows by that logic, no cultures are any worse either, by definition, and he agreed without hesitation.
The whole point of the liberal-arts portion of a university education today is to confuse the young mind, to chip away their allegiences to parents, authority, “the establishment”, etc, any sort of religious based mores or values, any sort of so-called individualist thinking, isolate and weed out free thinkers, etc. EVERYTHING is political with these folks.
If you really believe this, let me suggest the book War Before Civilization: The Myth of the Peaceful Savage by Lawrence H. Keeley. It quite irrefutably establishes that almost all primitive societies are far more violent than even those of the 20th century.
The average "primitive society" studied by him had violent death rates at least 10 times higher than those suffered in war during the 20th century.
IOW, if the 20th century had been as violent as the leftists' beloved "wise and peaceful indigenous peoples," 1B to 2B people would have been killed rather than the 100M to 200M that were.
The 20th century killed large numbers of people, but this is much more a function of the high population than of the intrinsic level of violence.