I'm a fan of Dick Francis's early novels, where the heroes are working hard to achieve their goals but haven't yet made it. As he became a very successful author, understandably his heroes got richer; when the baddies are after them, they hire Mercedes and book into five star hotels. And I find them more difficult to relate to.
Famous poor heroes: Cinderella, Katnis Everdeen, Harry Potter (briefly, till he turned out to have all that gold in Gringotts) Winston Smith, Cassandra in I Capture the Castle, Jane Eyre, Elizabeth Bennett, David Copperfield, Pip, the March sisters, Sam Spade, Jim Dixon, Han Solo, Rose Tyler, Dave Lister, Madame Bovary, Flora Poste, Gabriel Oak, Becky Sharp, Tess of the d'Urbervilles . . . add your suggestions in the Comments.
Famous rich heroes: Hamlet, Emma, and all those brooding kinky billionaires in that weird new genre, Billionaire Romance, that takes the Jane Eyre meme to ridiculous extremes. Have I missed anyone?
In Disraeli's novel Sybil, published in 1845, a working-class radical, Walter Gerard, describes England as being:
“Two nations; between whom there is no intercourse and no sympathy; who are as ignorant of each other’s habits, thoughts, and feelings, as if they were dwellers in different zones, or inhabitants of different planets; who are formed by a different breeding, are fed by a different food, are ordered by different manners, and are not governed by the same laws.”
“You speak of — ”said Egremont, hesitantly.
“The rich and the poor.”
And things haven't changed all that much, providing plenty of material for authors to get their teeth into.