What are the points Maya Angelou makes in her book?

I Know Why the Caged Bird Sings is an autobiographical look at the upbringing of author and poet Maya Angelou. She tackles issues such as abuse, abandonment, and discrimination with vigor, challenging the reader’s sensibilities throughout the text.
Perhaps the most obvious topic in this book is racism and discrimination. Angelou is taken to a white dentist who says “my policy is I’d rather stick my hand in a dog’s mouth than a n----r’s” (184), and her brother discovers the rotting corpse of a black man, prompting the family to cautiously inquire about the body (191–4). Although tackling a serious topic, Angelou allows room for humor: "People in Stamps used to say that the whites in our town were so prejudiced that a Negro couldn’t buy vanilla ice cream" (47).
This racial tension often results in a series of shifts, or displacements. Constantly moving between various homes and families creates a sense of instability that mirrors her experiences as an African American in this particular time period (the 1930s and 40s). In the book, the black community alternates between elation, as they experience when Joe Louis wins a legendary boxing match (129–132), and the weight of the oppression that defines their everyday lives.
The book goes back and forth between themes of light and dark, peace and conflict. On page 113, Bailey (Angelou’s older brother) receives a severe beating from Uncle Willie, and this violence is followed with a nighttime prayer. After a brutal sexual assault by her mother’s boyfriend (76–77), Angelou opts to walk home and go to bed rather than tell anyone in her family. There is a common theme of covering harsh things up, pretending that they aren't there in the hope that no one will find out, as Angelou covers up her pregnancy as a teenager.
https://pacs.ou.edu/blog/i-know-why-the-caged-bird-sings/