You won’t get your definition past the U.S. government.
They define a hispanic - or latino - as anyone descended from the peoples who originated on the Iberian peninsula, in addition to the Latin American countries.
Definition straight from the U.S. Census:
“Hispanics or Latinos are those people who classified themselves in one of the specific Spanish, Hispanic, or Latino categories listed on the Census 2010 questionnaire -”Mexican,” “Puerto Rican”, or “Cuban”-as well as those who indicate that they are “another Hispanic, Latino, or Spanish origin.” People who do not identify with one of the specific origins listed on the questionnaire but indicate that they are “another Hispanic, Latino, or Spanish origin” are those whose origins are from Spain, the Spanish-speaking countries of Central or South America, or the Dominican Republic. The terms “Hispanic,” “Latino,” and “Spanish” are used interchangeably”.
Aztecs, Mayans and Incans are simply aboriginal indigenous people who would be classified as such in the U.S. were they to not claim one of the other categories which might imply some Spaniard ancestry - i.e., Mestizos.
But Nauhuatl speaking Aztecs are really intense about not being hispanic or latino. They are Mexican, which is an anglicization of one of their subgroups - “meshican” is probably the best pronunciation.
And don’t call a Mayan or an Incan a hispanic or latino, at least not with a weapon nearby...you might not get out of there!
If someone with Aztec or Mayan blood is habling espanol, they are Latino/Hispanic.