Hitler and the Nazi Party weren't the first to hate the Jews. There was mass antisemitism in Austria and Germany after WWI due to many things, including rumors of "Backstabbing Jews" who contributed to the defeat of Germany in WWI and an association of Judaism and Communism (Well known communists such as Leon Trotsky, Béla Kun, and Ernst Toller were all Jewish). The Jews were a simple scapegoat to blame the problem on. It's easiest for them to say "those Jews made us loose the war" instead of actually addressing why they lost the war. As to why Jews are hated through out history, I'll lead you to this thread. If you want sources just ask.

To add to this, why has much of the world hated Jews throughout history?