See how often they participate in the script: HERE.
Character Story: Barnes is a good friend of the shaman of Kakariko Village, Renado. He also owns a small bomb shop in the town that needs repairs after the Invasion. Do not use your torch in his shop.
Race Story: Humans typically live peacefully with other races throughout all of Hyrule. The more specific Hylian race is a subcategory of humans. They can be differentiated by their ears -- Humans have rounded ears and Hylians have pointed ears.