Am I Native American if I'm Mexican?

Whether you are considered Native American if you are Mexican depends on both ancestry and how the terms are used legally in the US versus culturally in Mexico. Most Mexicans have significant Indigenous ancestry, often from Aztec, Maya, Zapotec, Mixtec, Otomi, and many other Indigenous peoples who lived in what is now Mexico for thousands of years before Spanish colonization. Genetically, the average Mexican has a large percentage of Indigenous DNA combined with European and sometimes African ancestry due to mestizaje. In that broad historical sense, many Mexicans are descendants of Native Americans from the continent of North America. However, in the United States, the term Native American has a specific legal and political meaning referring to members or descendants of tribes indigenous to what is now the United States, such as Navajo, Cherokee, Lakota, etc., and enrollment is based on tribal citizenship, not just DNA. So a person from Mexico would generally be described in the US census as Hispanic with Indigenous ancestry, or as Indigenous Mexican, but would not automatically be enrolled as Native American under US federal tribal law unless they also have ancestry from a US-recognized tribe and meet that tribe's enrollment criteria.