Nobody in the US think Spanish is a race rather than a nationality. There's an artificial "Hispanic" term politicians invented to encompass all Spanish speakers.

Ignorant Americans may conflate all from Central America as "Mexicans", but that's about it.

Most Americans who never studied the Spanish language are probably ignorant of the differences between Castilian Spanish and Spanish as used in the Americas.

Differences between "Castillian Spanish" (I don't like that term at all, more on that on [1]) and Latin-American Spanish are only on pronunciation of some consonants. The Royal Spanish Academy (Real Academia Española) accepts allow all of those dialects as rightful variants of Spanish language.

[1] What some politicians call "Castillian Spanish" is the Spanish language spoken in all parts of Spain. It is idiotic to call "Castillian" to a language were some dialects of Spanish (West/East-Andalusian and Canarian [from Canary Islands]) are very similar to Latin-American Spanish.

Both race and nationality are social constructs. Countries too.

Would you call "British" or "English" to a US-American citizen based on their language, then?