So I'm someone who is from and lives in a Central American country with a heavily indigenous population. It's true that a lot of us (myself included) are mestizo of mixed ancestry. But mestizo also just means mixed because a lot of us also have African ancestry that we never want to admit. I would be careful with calling most Mexicans indigenous. They may have indigenous ancestry but their culture is very much one that takes after Europeans. My country does the same thing with the Mayans. We have their imagery and make references to them, but that's only the Mayans of the past. We treat the modern ones like shit and being referred to as "indio" is seen as an insult.

What makes someone indigenous goes beyond ancestry. You have to be involved in the community and culture. Someone who's got Mayan ancestry but is completely homogenized into the dominant culture is no longer indigenous according to them. I have indigenous ancestry but I can't speak the language and communicate with the indigenous people in my area as an outsider looking in, instead as of one of the community. Therefore I'm not part that group and can't claim it.