See how often they participate in the script: HERE.
Character Story: Wife of Hanch, mother of Beth. Sera owns the single, small shop inside of Ordon Village. She sells Link his slingshot early after he helps find her lost cat who is also named Link.
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.