It's not true though. Slaves/black people are not the only people who built this country. That's just over the top militant ego talking.
The United States in the modern era is a culmination of 250 years of nation building. The country in 1850 looked completely different from the country in 1950. Every decade, the country continued to be built block after block, job after job, invention after invention, across multiple generations.
Immigrants (not just Hispanics, but in general) did help build the country. They came in doves during the Progressive Era of the early 1900's and took factory jobs, steel mills, took jobs building railroads and construction jobs. You will find this information in any historical research, study and analysis with a simple google search.
And yes among class lines, unions played a significant role in the development of this country and the middle class.
To get to where we are now, it took a wide variey of people and groups to get us here.