See how often they participate in the script: HERE.
Character Story: To be found with his mother, he helps Link by allowing him to warp out of temples and back in without needing to retrace his steps.
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.