A popular "argument" that is hugely popular on social media goes like this : "Americans slaughtered 100 million native Americans."
First, it's nonsense to claim that there were 100 million native Americans living in north America. Up to 18 million native Americans were living in North America around the 17th century.
On the whole, It is estimated that the population of Native people in the Americas was anything between tens of millions to over 100 million in pre Columbian times.
In any case, the native population declined to less than six million by 1650 in South America.
If you want to blame someone for the deaths of Native Americans, in south and north America, you should blame bubonic plague, chicken pox, pneumonic plague, cholera, diphtheria, influenza, measles, scarlet fever, smallpox, typhus, tuberculosis, and whooping cough that were brought by the European colonists.
The scope of the epidemics over the years was tremendous, killing possibly in excess of 90% of the population in the hardest hit areas, and creating possibly the greatest human catastrophe in history, far exceeding even the disaster of the Black Death of medieval Europe.
In fact It was the European germs that did most of the actual conquering of South and North America, as they decimated the local population and literally depopulated both South and North America out of their indigonous populations.
This is in no way should be interpreted as a defence of Spanish, English, French and American colonists horrendous, brutal crimes and actual conquest against the indigenous local population of south and north America.
Crimes which included enslavement, massacres, rape and plunder on an industrial scale, destruction of whole civilizations and way of life, and the uprooting and ethnic cleansing of whole populations and people.
However it is important to remember who, or actually what, was responsible for the deaths of the overwhelming majority of the indigenous population in the Americas, diseases, not people.
"Guns, Germs, and Steel." by Jared Diamond.
"Born to Die: Disease and New World Conquest." by Noble David Cook.