Immigrants are the only reason we have an America to begin with. However, our immigrant journeys differ tremendously. As you noted, African people were brought as slaves and to make room for new immigrants, Native Americans were almost completely killed.
However, going forward, America developed and thrived based on the immigrants who entered during the industrial revolution of the 1800s. They are important and should be respected at every level of our society.
I cannot stand to see them treat immigrants poorly. Anyone who comes to America and wants to be American should be able to, in my book.