Hi, @Armando! I hope you are well. Thanks for opening up this line of questioning! I have a similar question to @Jimmy_Sellers for the skeptic who would use this line of reasoning. Jimmy asked, ‘Is everything that Jesus said an original idea?’ and I would further ask, ‘Does Jesus’ teaching need to be original for the Gospels to be ‘historical’? (whatever that means…) I think that if one concludes that, yes, the teachings do need to be original in order for the source to be historical, then I question their ability to read history properly at all. Historicity is not tied to originality.
I would also contend that Jesus (the man, who lived for a specific period of time in a specific place) wasn’t concerned with being original; he was counter-cultural. He was a rabbi who brought fresh perspectives on the old law; he was not bringing something completely new. He did usher in a new age of spirituality and communion with God, but the Old is its foundation.
Another line of questioning to take would be to ask what the skeptic means by ‘original’. Because I would contend that Jesus, as the second person of the Trinity, was the origin of all things before He came in the flesh. As John writes in his Gospel:
In the beginning was the Word, and the Word was with God, and the Word was God. 2 He was with God in the beginning. 3 Through him all things were made; without him nothing was made that has been made. 4 In him was life, and that life was the light of all mankind.