Viewed in historical perspective and reading all her introspections in the book, Jane is INFP not INFJ.
In the movies, she's usually played as INFJ. It's all in her reasons for giving him up. (They were not based on cultural values but the values of her own heart and the lack of respect shown her, the dishonesty that she'd have to engage in.)
As far as her being INFJ just because the author is thought to be INFJ, it's very hard to write a well rounded character based on one's exact personality, in fact this is called a biographical trap or something like that. It would make more sense that she'd create the more dynamic character played off her dear beloved sister who probably also drove her to distraction at times.
And Emily makes Cathy in WH a ENFJ.
Sisterly love captured for all time in great characters that live on and on.
I thought Helen Burns was a clearer INFP than Jane Eyre. Helen Burns was the friend at Lowood School who died of consumption. The one who had to hang a sign saying "slattern" around her neck at one point.
Nah, Helen was ISFJ. She put up with way too much shit just because the societal standards of the time expected her to.
Idealistic INFP would not put up with that for long.
It's been a fair few years since I last read the book, but from memory she put up with everything she did because of her own (Christian) ideals, not because of the societal standards of the time. If my memory isn't misleading me, ISFJ is a bit of a ridiculous call for her.