Jews, mainly..But also, Czechs,Poles, Others.
no people would get randomly picked to be in the holocaust
This is a puzzling question. By definition a victim is 'involved' in a passive sense; they are picked on.
He was the Chancellor and leader of Germany and the one who masterminded the Holocaust. Hitler cannot be considered a mastermind, it was done in his name, but the overseeing was done by Himmler and the actual planning was done by people like Eichmann and Heydrich.
It depends who's doing the picking. I have picked, you have picked, they have picked, we have picked; but he / she / someone (named) / something has picked.
If you mean Sonderkommando, during the operation of the Nazi death camps (Holocaust) they were a picked group of male prisoners. They were forced, on pain of their own deaths, to dispose of the bodies of camp inmates that had been killed or died.
The Holocaust
Hitler's reason behind the Holocuast was that the Nazi's blames European Jews for the condition of the economy.
To remember the Holocaust.
The Holocaust is a concept not a person.
The Holocaust wasn't a war. Please see the related questions.
One aspect of the Holocaust is murder, there was a lot of killing in the Holocaust.
The Holocaust started in Europe.