Stephen Hawkins has claimed that we are absolutely doomed if we encounter ETs. This is largely based on the fear that we’ll wind up like the natives when the Spanish showed up at Hispaniola:
The Spaniards first assaulted the innocent Sheep, so qualified by the Almighty, as is premention’d, like most cruel Tygers, Wolves and Lions hunger-starv’d, studying nothing, for the space of Forty Years, after their first landing, but the Massacre of these Wretches, whom they have so inhumanely and barbarously butcher’d and harass’d with several kinds of Torments, never before known, or heard (of which you shall have some account in the following Discourse) that of Three Millions of Persons, which lived in Hispaniola itself, there is at present but the inconsiderable remnant of scarce Three Hundred. Nay the Isle of Cuba, which extends as far, as Valledolid in Spain is distant from Rome, lies now uncultivated, like a Desert, and intomb’d in its own Ruins. You may also find the Isles of St. John, and Jamaica, both large and fruitful places, unpeopled and desolate. The Lucayan Islands on the North Side, adjacent to Hispaniola and Cuba, which are Sixty in number, or thereabout, together with with those, vulgarly known by the name of the Gigantic Isles, and others, the most infertile whereof, exceeds the Royal Garden of Sevil in fruitfulness, a most Healthful and pleasant Climat, is now laid waste and uninhabited; and whereas, when the Spaniards first arriv’d here, about Five Hundred Thousand Men dwelt in it, they are now cut off, some by slaughter, and others ravished away by Force and Violence, to work in the Mines of Hispanioloa, which was destitute of Native Inhabitants
If we go back to the 1400s we were living in a resource constrained world before the industrial revolution. Before the Bubonic Plague put a temporary hold on population pressures in Europe, there were regular severe famines. The primary understanding of how to run an empire was from the Romans. That was conquer lands, enslave and receive tribute. The ancient world was even more violent.
Today we live in an era of enormous abundance and light population pressure. In the future, with advanced technology, the population pressure will probably be even lighter. A lot of the rapid decline in violence from previous eras is covered in the book “The Better Angles of Our Nature“. The universe is vast and, with terraforming, there are a large number of worlds throughout the universe that could be habitable. Thus we are probably viewed by the rest of the universe much like the population of North Sentinel Island. These violent natives are left alone to their own devices. The primary area of interest for extraterrestrials is probably our DNA and they can gather that all with minimal disruption of the inhabitants. Most likely they already did that centuries ago.