Antoinette is the protagonist and primary narrator of Wide Sargasso Sea by Jean Rhys, and her life is both tragic and complicated. She and her family are white and live on a plantation called Coulibri Estate in Jamaica. Antoinette is a white Creole, which should put her in a position of advantage on the island; however, after her father dies she and her mother and brother are left in poverty.
While her skin color should set her above the black Creoles, her poverty lowers her social position to something close to them. Of course this sets up an automatic antagonism between Antoinette and the blacks who serve her family and work the plantation. Because of this, she grows up in relative isolation. She has no white friends, and her only black friend (Tia) eventually leaves her, as well, after Antoinette calls Tia a "nigger." Tia calls Antoinette a "white nigger," and that both ends their friendship and encapsulates Antoinette's position on the island.
Your question asks what Antoinette thinks about people, and that varies based on who they are. In general, she is a loving girl who wants to have friends, fall in love, and be happy for the rest of her life. She is not deliberately unkind to anyone, but because of her circumstances she is ostracized and mocked by the black Creoles, her supposed social inferiors.
Her relations with her half-siblings is complicated, as is her relationship with her mother and brother. When Annette, Antoinette's mother, gets remarried, things get substantially worse for the girl. While she has always felt at home in her colorful and rather wild, tropical environment, Mr. Mason appears and insists on transforming everything into an English manor. This not only creates a personal loss for Antoinette but also creates new discord and resentment between the white and black cultures on the plantation.
Antoinette has deep feelings for several people, but she falls irrevocably in love with her husband. Even though the marriage was arranged, she loves Rochester and desperately wants him to love her in return. Other people get involved and partially destroy her chances for happiness, but the primary culprit is Rochester himself. He is resentful and feels as if he has been manipulated into this relationship (which he has), and he is is simply unwilling to think anything but the worst about his wife.
Though there are exceptions, the black Creole women in this novel are portrayed as vindictive and selfish. They are envious of whites and disdainful of anyone they can afford to be unkind to--including Antoinette. She says:
They hated us. They called us white cockroaches. Let sleeping dogs lie. One day a little girl followed me singing, "Go away white cockroach, go away, go away."
Undoubtedly this antagonism is due, in large part, to the political and social conditions on the island at this time. The abolition of slavery is imminent, which adds tension to all relations between whites and blacks, even those which might be considered friendships. White ownership of slaves obviously builds resentment, and the blacks outnumber the whites many times over. By the time Antoinette leaves the island, the black Creoles are bold in their hatred and manipulation of the white family, as evidenced by Amelie's apparent planned seduction of Antoinette's husband.
This novel has many complications, including insanity and fidelity; however, the most significant and violent complication in this island paradise is the clash of cultures and ethnicities.