Question

Do you think "Spanish," is an appropriate way to classify a person's ethnicity?

Answer 1

no it isn't spanish is just a language it is a latin root langauage what you could classify a person whom speaks spanish are hispanic/latino

Answer 2

If you are from Spain.

Answer 3

Even if you are from Spain, it would be Spaniard, and that would be a person's nationality, not ethnicity. Though sometimes, "Spanish" is used instead of "Spaniard. But as @bbb911 mentions, the ethnicity would be hispanic/latino.