Nonsense. The conquistadors were indeed appalling in many ways, but no they did not go for full on genocide. The diseases that came with them killed off possibly 90% of the New World population regardless of what they did or didn't do. They were slavers for a time and even that was fought against quite vigorously by a surprising number of other Europeans (read for example about Bartolomé de las Casas). Much of the modern narrative mixes up an essentially unstoppable and non-deliberate mass die-off from European diseases with genocide. The two things were not the same even if the conquistadors also did often butcher native populations in specific contexts. As for the Aztecs, they truly were barbarous to their subjects. Their culture, for all its sophistication and many fascinating aspects, was based on an enormous amount of ritual and practical violence across many areas. There's no white washing this for PC reasons if you read even a moderate amount of literature about their empire. Even the Spanish didn't practice the ritual slaughter of over 20,000 people in just a few days simply for the sake of a religious festival. The Aztecs did indeed do this at times.

The conquistadors were not set on carrying out genocide, and did not carry out genocide. They were just vastly more advanced than the nations they encountered and consequently were able to conquer many of them.