The Victorian era economy class lines were rather rigid. And if the children did not marry in descdending order in arranged marriages, there was the belief that something was wrong or troubled. In P&P there was the disappearance of one of the sisters, and this could possibly have ruined the reputation of the family, meaning none of the other sisters would be able to marry and would be thought of as scandalous or promiscuous.
The class issue comes to a head in that Lizzie and Darcy's legitimately-pursued relationship is despised by a local ducchess or marquesse, Katherine De Bourg, his guardian. That's because Lizzie's father is of lower standing.
Lizzie's initial impressions of Darcy are very negative compared to where they will end up.
The double solution of Mr. Darcy the hero is that of clearing up the debts of the wandering younger sister's boyfriend (a half brother of Darcy) and paying for their wedding, and then truly loving Lizzie in spite of the duchess' preferences. The class barrier is overcome by a kind distribution of money, and the family reputation is restored by arranging the wedding.
Austen seems to have preferred to have the individual with money do the kind thing; it would be interesting to hear if she would have favored government programs attempting the same. And she puts love forward as a solution to class prejudice and pride.