Who was the first Mexican?

The label "Mexican" is a relatively new designation for a person who is a citizen of Mexico.

Who was the first Mexican?
Raramuris indigenous peoples costumes. 

The first humans in Mexico are believed to have arrived around 20,000 years ago, during the last ice age, when the lower sea levels allowed people to migrate across land bridges that connected North and South America. These early inhabitants of Mexico were indigenous peoples who belonged to various groups and cultures, including the Olmec, Maya, and Aztecs.

The Olmec civilization, which is thought to have arisen around 1400 BC, is considered to be the first major civilization in Mexico. The Olmecs were skilled farmers, artisans, and engineers who developed a complex system of government and built large cities with monumental architecture, including pyramids and ceremonial centers.

The Maya civilization, which flourished in Mexico and Central America from about 2000 BC to 1500 AD, made significant contributions to art, architecture, astronomy, and mathematics. The Aztecs, who emerged in the 14th century AD, built a powerful empire in Mexico that included a sophisticated system of government, religion, and trade.

It is important to note that the term "Mexican" is a modern label that refers to a person who is a citizen of Mexico. The indigenous peoples of Mexico, who have lived in the region for thousands of years, have their own distinct cultures and identities.