The phrase "original author" refers to the person who created or wrote something first. They are the one who came up with the original idea or content. Full definition
It is a literacy crime and all information sources must be properly referenced to give due credit to original authors of the work. (coverlettersandresume.com)
• Golden art plate featuring Giorno & Gold Experience illustrations from original author Hirohiko Araki (crunchyroll.com)