Final answer:
Mrs. Cullinan called Margaret "Mary" as a sign of disrespect, implying that Margaret's actual identity was insignificant, which was insulting to Maya Angelou because it reflected a history of African Americans being deprived of their personal identity and heritage.
Step-by-step explanation:
The question of why Mrs. Cullinan called Margaret "Mary" and its implications reflects a theme often explored in literature, particularly relating to personal identity and respect. In Maya Angelou's autobiography, I Know Why the Caged Bird Sings, Mrs. Cullinan's decision to change Margaret's name to something she deemed more suitable is an act of disrespect and dehumanization. It implies Margaret's identity is insignificant and can be overridden by Mrs. Cullinan's preference, stripping her of personal agency.
This act is insulting to Maya because it is not only a denial of her given name but also a symbol of the power imbalance between her and Mrs. Cullinan. By renaming her, Mrs. Cullinan exhibits her perceived superiority and control over Maya's identity, which is deeply demeaning. Such an action reflects the broader historical context of African Americans being stripped of their identity and heritage during and after slavery in America.
The insensitive renaming signifies how African Americans were often not given the basic respect of being addressed by their actual names, a sign of personal dignity and identity. This is why it is an insult to Maya, as it suggests her true name, and implicitly her true self, is neither known nor acknowledged by Mrs. Cullinan.