This question always takes me by surprise. I am reminded of myself at about age eleven, when I figured out about the relationship between sex and pregnancy. I was watching Johnny Belinda — a movie about a deaf woman who is raped and has a baby, a story set maybe in the forties or so — and I realized with huge surprise, disquiet and even disbelief that those people knew that sex led to having babies! I couldn’t believe it. I was positive this discovery must be very recent.
Women in the late 18th century were very much aware of their lot in life. Not all of them protested publicly (most of them did not have the means to do so); certainly not all of them had any objection to the status quo. But many did.
While the struggle was a hard one, women of the period wrote fiction and poetry and social commentary. Women were extremely active in the abolitionist movement (which began in Europe, not in the U.S.); they founded hospitals and schools. Mary Wollstonecroft was not alone in calling for a more reasonable and fair approach to educating girls. So no, Elizabeth is not at all ahead of her time. She is unusual, yes, but that’s why she’s interesting.