All Americans have immigrant ancestors, many of whom came to America not knowing English. How many of the 17th, 18th and 19th Century non-English speaking immigrants who came to America as adults learned English? I don’t know. I know that my great-great grandparents who came to Davenport in the 1880s from Schleswig-Holstein spoke Platt-Deutsch (low German) at least to their children their whole lives. My father remembers visiting his great-grandmother and having his mother and aunts translate.
Of course, those who came as young children and the children of the immigrants who were born here learned English perfectly even though English was not spoken at home.
How about your ancestors? Did those who came as adults not knowing English learn English?