In the top 30 in 1880, I believe. Yeah, I think it originally came from Jane not from Jennifer. Isn't there any chance she could have known about it, though? Ancestors or books? I remember that at least Benjamin was named for someone maybe Jennifer was too.
I doubt it, but the book's possible. Jennifer probably became popular in America because of Jennifer Jones (b. 1919), although that wasn't even her real name.
When you click on Jennifer it says that there was a play in which a character was named Jennifer in 1906. Yeah, I guess it's extremely unlikely but still possible.