Beneatha is a complicated character who embodies aspects of stereotypes but still comes across as authentic. The stereotypical aspects pertain to various aspects of her identity: She is barely out of her teens and has many adolescent longings, she aspires to move beyond the race and class limitations of her family's position, and she is fascinated with African culture.
The complexity of Beneatha's character is conveyed in part through Lorraine Hansberry's detailed description and stage directions at the point in Act I, Scene I when Beneatha first appears. It includes a discussion of her speech patterns, which reflect some of the identity issues she is experiencing.
Her conflicted but affectionate relationship with her older brother also comes across as authentic, as she teases him mercilessly. Picking and choosing elements of African culture, and developing an interest in an African student could be considered stereotypical, but her perspective also changes at various points.
More than Beneatha, the two young men interested in her and the diametrically opposed relationships seem stereotypical. George, the conventional, unimaginative, boring good guy whom she finally rejects is strongly contrasted to Asagai, the foreign, fascinating man who charms her with Yoruba culture and dress. The scenes with them do not leave much room for her character development, as they do not come across as individuals.