When considering all of the Americas, I've seen estimates of upwards to 100 million, which is a totally unjustified obscenity. In North America alone, I've seen anywhere from 10 million to 30 million.
I've realized recently, as an American citizen, another absolute lie that we have been led on for our entire lives. When we look at where Germany is today in terms of their own history, they fully acknowledge the fact that the Holocaust did happen, however stigmatized it may be. Compared to other genocides and killing campaigns carried out by the Stalins and Khans and Hitlers of history, none can stand up to a whopping 100 million people, so far as my knowledge of human history goes. You could maybe say that a great deal of these deaths were a result of unintentional smallpox cases that quickly killed the majority of that 100 million, but I do not for one second, believe that Europeans went into the Americas without knowing what germs they carried, as well as the affects those germs would have on a population of non-immune people from across the pond. This was during the Renaissance, when mysticism and science and art infected Europe, and where any number of biologists surely had to know this would happen. It's not hard to find out the method of disease related casualties, given the amount of time that great Britain, Spain, France, etc... have been around, and the fact that they're basically the forefathers of modern day science.
If I'm missing anything here, please give me a good learnin'.
Honestly, there isn't a good way to say this except bluntly: Every single claim you made is wrong.
First of all, there probably weren't 100 million Pre-Columbian people in the Americas. The absolute highest numbers I have ever seen are in the 120-140 million range and those are widely considered to be trash. it's more widely accepted that the value is well south of 100 million, perhaps as few as 10-20 million or as many as 60 million. However I will not pretend either of these ranges are entirely reliable and there is a lively academic debate continuing as to the specific range. We simply don't know that much beyond crude estimates.
Secondly, the countries of the Americas do not generally deny the atrocities committed during their histories. The US and Canada have gone so far as to issue formal apologies to native peoples for past grievances. Other nations, Mexico and Brazil being the first examples that come to mind, have offered apologies for specific events and acknowledge the general history of their countries, albeit without full apologies.
Thirdly, comparing the European colonization of the Americas to the actions of either Nazi Germany or the USSR is entirely disingenuous. There is no evidence there were widespread policies of deliberate extermination. Extermination policies were practiced to varying degrees of effectiveness in specific regions, but this is an entirely different discussion. The border states of Chihuahua, Sonora, and Durango had several explicit policies on the extermination of Apaches between 1821 and 1840. In no case were any of the above remotely comparable to the later atrocities you mentioned. They occurred in substantially different contexts and with vastly different motivations on every side. Also, genocide olympics are bad.
I do not for one second, believe that Europeans went into the Americas without knowing what germs they carried...
How could they possibly have known? Biology as a distinct field wouldn't exist for at least a full century after the Columbian expeditions. The first microscope (let alone a good one) wouldn't be invented for many decades. Epidemiology did not exist. The first feeble stabs at microbiology would not be undertaken for the next 50 years. None of the people who later became important as foundational figures in Biology (Hooke, Leeuwenhoek, Gram...) would be born for decades. The only person who would become important in that area that was even ALIVE at the time was Fracastoro, a boy of 15 by the time the first of the Columbian expeditions left. Not only that, no one in Southern Europe even knew the Americas existed before the expeditions, let alone what diseases they were or were not resistant to. Once they did meet the natives, how would they have discovered their lack of immunity? Vaccines and antibody tests were not a thing in the 15th century. Once people start getting sick, you're already too late.
The explorers could not have even begun to predict the plagues that they would bring. There is no way, shape, or form they could possibly have obtained the necessary knowledge without aliens.