Nietzsche's Overman is not to be construed in evolutionary terms. It is an existentialist concept. Try actually reading
Thus Spoke Zarathustra, Apostle.
Nazism has very little to do with Nietzsche and much more to do with capitalism and Christianity. Capitalism is the creator of racism, and Christianity is and always has been the basis of anti-Semitism for the past 2,000 years.