What was the primary purpose of the german racial purity laws?

For years, before becoming Chancellor of Germany, Adolf Hitler was obsessed with ideas about race. In his speeches and writings, Hitler spread his belief in the racial "purity" and superiority of the "German race", what he called a "superior Aryan race." He declared that his race should remain pure in order to take control of the world someday. For Hitler, the "Aryan" ideal was blond, blue-eyed and tall.

so they can differentiate themselves from others as they saw themselves as the superior race. the star was basically a symbol that meant you are a less of a person than i am because of my race. the star was also degrading for those who had to wear it because they were aware of this and the nazis used the notion to make them feel less like a person.