How are race, gender, and class addressed in Oliver Optic's Rich and Humble?

While class does play a role in Rich and Humble, race and class aren't addressed by William Taylor Adams (Oliver Opic's real name) in the book. There are no struggles or scenes devoted to gender roles, racial issues in society, or anything of that type.

Class plays the biggest role in the novel, because Bertha starts out as a upper-class girl living on a wealthy estate and is then cast out without a place to go, without friends, and without money. She has to work to prove her father's innocence and reclaim her estate.

Even before Bertha has to become a member of the working class, she has empathy for the poor. Adams writes of an area near Woodhill where Bertha lives: "This was Dunk's Hollow, to whose poor and neglected little ones Bertha Grant had become a ministering angel." She is kind and helpful to people in the social classes below her.

This is contrasted later when her origins are revealed to her employer Mrs. Byron. The woman likes Bertha as a governess until she finds out that Mr. Grant is in jail for fraud. Once that truth is exposed, she views Bertha as a liar, fraud, and thief, and tries to fire her without pay. Her treatment of Bertha, a servant, exposes the negative views of the privileged toward the working class.

Further, when Bertha is cast out by Mrs. Byron, a member of the servant class gives her a place to stay to make sure she's safe. Peter tells her that there's nowhere safe to stay nearby and invites her back to his home. He and his wife give her a comfortable place to stay, and he drives her to the ferry the next day. 

Adams also shows the contrast between two different societies near Woodhill. First, he describes Dunk's Hollow, saying:

Dunk's Hollow had a very bad name in the neighborhood and man, woman, or child who came from there was deemed a reproach to the race. There was only one shop at the Hollow, and that was the principal source of all its miserty, for its chief trade was in liquor, pipes, and tobacco.

Next, he describes another nearby town:

On the opposite side of the river was the thriving village of Whitestone, in surprising contrast with the place just described. It contained four or five thousand inhabitants, with all the appointments of modern civilization, including a racecourse, half a dozen billiard saloons, where better and liquor drinking were the principal recreations, and as many bowling alleys and fashionable oyster shops.

The contrasting descriptions of the two different communities shows the differences in how people see the different classes of people. For example, liquor is clearly seen as negative in Dunk's Hollow. Liquor in Whitestone is considered a part of modern civilization, set up to lure in the rich sons of the local estate owners.

Class plays a role in Rich and Humble as it contrasts the behaviors and actions of the characters. It also serves as the background of Bertha's struggle as she transitions from being a wealthy, cosseted girl to a member of the servant class and then, finally, back to wealth.