Having a friend that is a Jew doesn’t make someone less of an anti-Semite, I’m not making accusations, just pointing that out. And many people in America still view Jews as a sort of “other”, similar to the opinions of some of the people of Europe. Jews, in most places, will never fully assimilate while anti-semitic rhetoric and acts exist. More importantly, like most ethnicities, the Jews maintain languages and traditions separate from that of other peoples. Therefor, in one of our many ethno-specific languages (Yiddish), and even in the Torah, the word goyim means means gentile, or non-Jew. It can be used mockingly, derogatorily or descriptively but that does not attach the meaning, the individual speaking does, not whoever is being spoken to or observes the interaction. Many other ethno-specific languages, such as Rromani (which I am far from an expert on) have words for “the others”. You keep people separated from you for long enough, with pogroms, expulsions, mass genocide, ghettos, and yeah, we develop ways of referring to the non-Jews.