There is also a significance in the children facing and overcoming their fear in Boo, and their realisation that blind ignorance masks reality. Boo is no longer a squirrel-eating monster but a compassionate, honourable human being. In reading the novel, there is the hope that as a result of the text the readers could face and overcome the fear of difference and realise the blind ignorance that is racial prejudice.
With respect to what has been remarked upon so perceptively, there is, indeed, a reciprocal growth as both Boo Radley and Scout and Jem have "climbed into [each other's] skin and walked around in it." With Boo's emergence as a human being, also, Scout becomes more humane, thus giving reinforcement to Harper Lee's key theme, and proving clearly that it is "a sin to kill a mockingbird" as Sheriff Tate determines that Bob Ewell "fell on his knife."
Boo Radley has become a friend to the children. He has watched them play each day and has come to care for them. It is fitting that "Boo" saves the children in that he is a mockingbird. He has been a victim for his entire life. Ironically, Boo becomes an unlikely hero, rising up above the circumstances surrounding his own abuse, to take on the years of abuse at the hands of his father and then of Nathan Radley, his brother.
I think it's fitting because in a way, they have saved him. Boo had been walled up in that house for years, feeling like he wasn't even human. But gradually, he became interested in the kids and their doings. As he watched them and (sort of) interacted with them, he became more human. In that way, they saved him, or at least helped him save himself.
Because of that, it is fitting that he should (literally) save them at the end of the book.
Boo Radley has always been the protector of the children of To Kill a Mockingbird. Even when Jem and Scout feared him as the ghoul of the neighborhood, Boo attempted to befriend them with gifts in the secret knothole. When Jem lost his pants in the Radley's barbed-wire fence, it was Boo who mended and folded them. On the night of the fire, it was Boo who stealthily wrapped the blanket around the unknowing Scout to warm her. Unbeknownst to the children, Boo was always keeping an eye on them, and when he discovered Bob Ewell stalking them on the fateful Halloween night, Boo saved their lives. It provided the only opportunity for Boo to make an actual appearance in the novel, concluding the author's brilliant character sketch of one of American literature's most mysterious heroes.
Boo represents the mystery of childhood. By the end of the book, the children have experienced so much that they have basically grown up. Therefore, when they learn the truth about Boo Radley a final chapter of their childhood closes. They learn that he is not scary or evil, but rather shy and sickly.
It is fitting that Boo saves Scout becomes the story comes full circle. At the beginning of the book, Boo Radley is a mysterious but malevolent force in the children's lives. As time goes on, he becomes less and less frightening to them and they become just curious. They start to see that his is a sad story, and he might just be lonely or shy. They realize there is more to Boo Radley.
It is fitting that Boo Radley saves Jem and Scout and the end of To Kill a Mockingbird because it shows it was simply prejudice and fear of the unknown htat led the children to be frightened of Boo.
The kids always feared Boo, thought him a terrible person, when in reality if they were only to educate themselves (ie. meet him) they would learn that he was not the monster they had thought him.
This blends in with the theme of prejudice as the children felt secure in their misconceptions, only to realize their missteps after Boo saved them.