Who is Uncle Win from Jackaroo: A Novel of the Kingdom and what is their importance?

Uncle Win is Da's brother and Gwyn's uncle. Once engaged to Gwyn's mother, he was set to inherit the inn from his father. He also dressed as Jackaroo in his spare time and went around the area saving the citizens. It implied that the costume Gwyn discovers originally belonged to him. When a prisoner arrives to be quartered at the inn on the way to his execution, the family slowly realizes that he is none other than Win. Knowing this, Gwyn tries to save him, dressed as Jackaroo. However, knowing that Jackaroo is a myth (having played him himself), Win just laughs and tells her that he has accepted his fate. He goes to his hanging peacefully; Burt claims the body for Gwyn's family, without letting on why he is doing so.