Yeah, historically Japan started getting words from Chinese in the late Kōfun period (5th-6th century AD). The first Europeans didn’t set foot in Japan until the 16th century, so Japanese would have been incorporating Chinese words long before they even knew what white people were. It’s very likely that Japanese people’s first experience of white people was through stories told to them by Chinese people.
History aside, though, often when you’re talking about what kind of person someone is, it’s a single word with a compound kanji (there are some exceptions that are compound words, like 恋人 - こいびと - lover, or 村人 - むらびと - villager, but they’re not that common). You’re talking about a person with a specific attribute, and that attribute is just folded into being part of the word. It’s kind of like how ‘fireman’ is one word in English, but admittedly that example glosses over what I already said about the difference between compound words and compound kanji.
Incidentally, when you have compound kanji ending in 人, if the ‘type’ you’re talking about is a permanent or not easily changeable state, then 人 is normally read as じん, and if it’s a temporary or easily changeable state (including but not limited to occupations), then it’s normally read as にん. I think a lot of people have trouble remembering when to use which one.