Semite doesn't mean "semi". People who are semetic are descended from Noah's son, Shem. jooish people openly call themselves Ashkenzais. In Gen 10, it breaks down the family tree. Ashkenaz, descended from Japheth, Noah's other son that was white. Ashkenaz = Ashkenazi is German.
Hitler didn't hate them because they were "mixed with black", he hated them because of the way they operated after the Treaty of Versailles. They were oppressing and killing the German economy.