"Here's the deal: you either make moral choices and judgments in your own life, or you don't.
Europeans have long demonstrated that they don't:
I don't think the unimpeded rise of Nazism and the accompanying anti-Semitism was just some anomalous case."
America had slavery, genocide against the Indians, lynch mobs against blacks, and legally-enforced racial segregation until the 1960s. When one lives in a glass house, it is best to not throw stones. There is not a noticeably more moral history on either side of the Atlantic.
All of which we confronted, rallied against, and brought to justice. There's a difference between a nation that can correct perturbations from a civil society and those nations that let them diverge into world wars.
Slavery was a legacy of our colonial past. We eliminated it with a great sacrifice of blood and treasure. We addressed segregation and racial strife. Today, America is far more tolerant than Europe when it comes to assimilation of minorities. It is not a matter of throwing stones. Many Europeans came to America to escape religious persecution and oppression.
Genocide is a loaded word. It was never the policy of the USG to eliminate all Indians. It was the policy of Nazi Germany to eliminate all Jews. To compare what happened to the Indians to the Holocaust is an insult to those who died by the millions in the concentration camps. America did not initiate WWI or WWII, which resulted in the deaths of more than 75 million. We did not give the world communism, facism or socialism.