If you want to be literal-the people who were around to celebrate a thankgiving in St. Augustine Florida weren’t Mexicans-they were Spaniards-most were from Spain-not from the part of Spanish territory called Mexico. Pilgrims weren’t American, either unless they were born in America-the only Americans here when the Europeans and the Brits-including pilgrims-arrived were the Native American/Indians-so they were the only Americans at any of the Thanksgiving dinners anywhere on this continent before at least 1776. The American continent was divided into colonies/territories-no countries.
My ancestors were from Spain-they came to Mexico from Spain in the late 1500’s or so-technically speaking, they were not Mexicans because they were not born there-and it was just part of New Spain-not a country yet-they came to Texas and NM around 1780, but none of that was part of the Brit colonies-even Louisiana had not been given back to France by Spain in 1800, and there were only the former colonies to call a country/USA in 1800...
The IQ at FR has been declining for years, but that comment stands out all the same.