I'm going to assume you mean 19th century? Depending what early entails, you're either already in Mexico or in the Spanish Empire if you're in Texas.

Before 1821, you'd be in the Spanish Empire and no one would be around to care what colour you are, Spanish Texas was very sparsely populated.

Heading toward "Mexico" and the actually populated areas of the country - you'd probably be considered enslaveable in the Spanish Empire and treated as such.

After 1821, the situation regarding slavery in Mexico gets confusing. Many Mexicans wanted abolition in their new nation, but out of fears of economic turmoil this was carried out gradually, so depending on if you were born in Texas as a slave, or traded into the state would determine your status.

I think you mean 19th century.