The amount of effort that leftists can put into purely semantic arguments will never cease to amaze me. Who freaking cares whether or not a group of people that could barely build permanent structures used the exact same categorization of sexuality as modern Tumblr users do? That does nothing to disprove the common-sense fact that heterosexual relations have been present (and the norm) in every single culture throughout human history. Gender and sexuality are not social constructs, and even if they were, that would not be a sufficient argument to show that we ought to deviate from or abandon them.
That is a stereotyped and demonstrably false claim that is easily disproven by a simple Google search. The Aztec city of Tenochitlan had a population of over 200,000 - making it one of the largest cities in the world at the time - before it was decimated by disease and conquest. What is not often known is how advanced and prosperous the Central and South American Native Empires were. The Incan Empire functioned as a sort of pre-modern welfare state - among other things it cared for the sick and old, ensured clothing and other basic necessities for the citzenry, and provided food supplies should the crops fail - resulting in considerably higher living standards for commoners than in the Old World. During their conquest of the Empire, Pizarro and the conquistadors were astonished at the sheer lack of beggars and vagrants, so unlike their homeland in poor old Europe.