作者 and 主人公: the creator and the central character
Compare a creator placing a secret in characters’ names with a protagonist who grew up in a small town. Do not transfer an event in the story into the creator’s biography.
The person who creates a work
作者 (さくしゃ) means an author or creator. 「作者は登場人物の名前に秘密を込めた。」 says the creator put a secret into the characters’ names.
「展示室の入口に作者の略歴が掲示されている。」 says a short biography of the creator is posted at the exhibition-room entrance. 作者 can refer to a visual artist as well as a novelist.
The central character in a story
主人公 (しゅじんこう) means the protagonist. 「この物語の主人公は小さな町で育った。」 says this story’s central character grew up in a small town.
「観客は主人公の意外な決断に驚いた。」 says the audience was surprised by the protagonist’s unexpected decision. The character making the decision and the audience reacting have different roles.
Creation and events within the work
Putting a secret into characters’ names concerns the creator’s work. Growing up in a small town and making an unexpected decision concern the protagonist within the work.
A work may connect the creator’s experiences with the protagonist’s, but these examples do not establish that they are the same person. Do not make the protagonist’s childhood location the creator’s biography.
Who grew up in a small town in 「この物語の主人公は小さな町で育った。」?
Show the answer and why
The story’s protagonist. This sentence does not establish that the creator of the work also grew up in a small town.