What does this quote mean? “Some of us have chosen America as the land of our adoption; the rest have come from those who did the same”

Answer 1

Judge Learned Hand pointed out that everyone is either an immigrant or descended from immigrants.

http://www.digitalhistory.uh.edu/disp_textbook.cfm?smtID=3&psid=1199

Answer 2

Some are the people who immigrated from another country, and "the rest" are their descendants.

Examples: My maternal great-grandparents immigrated from Germany and Ireland; their children, grandchildren, great-grandchildren, etc., are descendants of those 4 people.

Answer 3

All of us are immigrants who have adopted America or the offspring of those immigrants. This includes even the American Indians, who migrated here hundreds or thousands of years ago.