In the 19th century Biblical names were very common, then went out of fashion. The idea of a farmer being a "rube" probably arose from people thinking that Reuben was a typical farmer's name.
Louis Adamic, an immigrant from Slovenia, wrote a lot on immigrant-related topics. I read something by him where he talks about a man in Pennsylvania with a typical Polish name who couldn't get hired as a teacher despite being well qualified, until he changed his last name to Sullivan. That would have been probably in the 1920s or 1930s.
Back in those days a number of people with Jewish, Italian, German, or Polish names anglicized them for professional reasons. In some cities with large Irish populations, I’ve read that Jewish or Italian boxers would change their names to an Irish name and even call themselves Irish Mike McBride or Irish Dan Malone. And of course, many people in showbiz anglicized/prettified their ethnic names i.e. Frances Gumm became Judy Garland.