Why is the Holocaust central to the post World War II concern with human rights?

The Holocaust is one of the most horrific and treacherous events that happened in European history. It does not even go far enough to say that the Holocaust was a human rights violation. It was a complete disregard by Nazis of almost every single human right that Holocaust victims possessed. The Holocaust delineates everything that a nation should not do to its people. As I look down my list of Internationally Recognized Human Rights, I literally cannot find one that was not violated during the Holocaust. It violated the most basic right to life, to an identity as a human being living on this planet Earth.
While walking through the Shoah memorial I became extremely emotional. I still cannot grasp how any groups of people are able to do some of the things that happened in the Holocaust to other human beings. What I don’t understand most of all about the Holocaust is how it went on for so long. I think the biggest human rights issue that may have to be noted is the lack of interference between nation-states and Nazi Germany. Instead of taking action when Global Powers became aware of what was happening at the concentration camps to millions of Jews and several other minorities, the Global Powers just turned their backs in order to avoid confrontation. I think that is the most immoral and flabbergasting occurrence of them all. Who could those victims turn to if the whole world turned their back on them until it was convenient to step in? This is an important message that I hope has been carried with all different nation-states around the world.
I am very grateful for this opportunity I had to further explore the treacheries of the Holocaust. It has opened my eyes to what I have to be grateful for, and how much the world still has to work on, until we can ultimately conquer freedom for all six billion of us.