Native language, Navajo and Sioux came from Asia when the Amerindians crossed the land bridge in Alaska some 10,000 years ago. Spanish, was not "here" first, it was in Latin America or South America first, though arguably Portuguese was there first.
And the issue isn't, what was here first, the issue is, why do we bend over backwards to accommodate people who have such a disrespect for our nation that they are not willing to learn the common language.
As far as Amerindian languages that were here first, I'd say Tuscarora, Mohawk or Oneida.
Now, supposing I wanted to go to the Netherlands, I would imagine that I would probably engage myself in learning Dutch first, same as if I wanted to go to Italy, I would learn Italian, and Mandarin Chinese if I was going to go to Beijing.
Objections, based on the fact that we are supposed to be a melting pot are retarded. How are we supposed to be a melting pot, if instead of ensuring that everyone assimilates into our culture they remain separate?
Perhaps, you've never seen what happens after a soup goes cold, it separates out into layers, where as when the soup is heated it all becomes a relatively homogeneous mass with all parts included.
Instead of ensuring Unity, you are ensuring division. Divisions that politicians usually take advantage of to create voting "blocs" for their own gain.