One of the most common frustrations I hear about from writers of both original and fan fiction is the need for character names. A number of resources have been developed to help writers create names simply because it's such a frequent problem (Ex:
Seventh Santum name generators). It's not as if Austen had the internet at her fingertips to browse for names, the poor girl.
Looking at each of Austen's characters named Jane, we find a key secondary character but not the main protagonist of the story in which they appear. Their family name and relationship to other characters is far more important than their first name. In my opinion, this is a signal from Austen that she didn't want to spend the effort on creating a given name with too much consequence, expending energy instead on the relationships that character had with the key protagonist or their function within the story arc.
The easy solution?
Jane.Secondly, a power law of distribution may have made Jane (and Elizabeth/Mary/Anne) given names most likely to be used by Austen. The popularity of a given name may have simply made the choice obvious at that time. Note this paper,
First Name Popularity in England and Wales over the past Thousand Years — at one point, Jane was the first name shared by 16% of the female population (~1530), and the top ten names were shared across 84%. Of course there would be a Jane (and Elizabeth/Mary/Anne/so on) in nearly every Austen story if these given names were the most popular at that time.
A story would not appear authentic or feel anachronistic without names mirroring those used most frequently. Readers would have felt like they were reading a fantasy novel to find Elizabeth Bennet's older sister was named Kaylee, Lakeisha, or Skylar, but completely at home and ready to suspend belief if offered a Jane.
I also suspect Austen selected other character names for reasons that are less obvious, but somewhat explanatory. Elizabeth in P&P, for example, is the "queen regnant" of the story; her sister Jane is not. The other sisters are given extremely popular names (Mary/Catherine) because they are not the focal point of the story.
Lydia, however, is named in a way that helps her stand out from her sisters; the
Biblical meaning of her name flags her role as being a counterpoint to P&P's "queen." Her role would definitely NOT be suited to the name Jane.
