It was actually a colony for quite some time. So, to say that everyone who came here was an immigrant is essentially a lie. It was a British colony and British people that moved there weren't immigrating. But those are just semantics.
Before America became a country, there were people here. They had a backwards culture and constantly killed each other. We civilized this place and brought our culture and made a country.
The 1607-1776 people MADE the country, so...... not really irrelevant.
It was influenced greatly by people before 1776, but after that it became American culture. Native American culture has very little to no influence on the values we have, so their culture is irrelevant, while the settlers' is not.
I never said that people who settled after 1776 weren't immigrants. The whole point of this was to say that not all immigrants are the same and that we have had periods in which we didn't accept large amounts of immigrants for long periods as we have since the 1960s.
Tell me, how are 17th and 18th century British colonists or even 19th century Irish immigrants the same as 21st century Mexican immigrants? Are their cultures the same? Are their incentives for coming to our country the exact same? Are their relative education levels to native citizens the same? Are they learning our language at the exact same rates? Are they assimilating the same? Are America's social, economic, and political climates the exact same as 200-300 years ago?
Likely none of these are the same between groups, so of course not all immigrants are equal and not all will assimilate as well.