The first issue one needs to consider in thinking about how Mandela is portrayed in Long Walk to Freedom: The Autobiography of Nelson Mandela, is that Mandela is not a literary character constructed by an imaginative writer, but rather a real human being writing about his own experiences as a black man living in South Africa under apartheid and his role in overthrowing apartheid and creating a new democratic South Africa. Although he can use literary models to shape his self-portrayal, much of the narrative is determined by actual historical events.
Mandela is the protagonist of the autobiography, and a fully-rounded character who develops over time from a child learning the traditional Xhosa skills of cattle-herding and warfare to student to rebel to political prisoner and key figure in the African National Congress.
Although Mandela displays personal modesty in his recounting of the events, he is one of the great heroic figures of the modern world, and perhaps the most important element of that heroism, and his greatest triumph was his refusal to be vindictive and his willingness to negotiate with the people who had treated him so brutally. As one reads the book, one gets a sense of his heroic stature.