That literary device was in use for several hundred years. It's highly unlikely, if not impossible, that actual eyewitnesses wrote what came to be chosen to include in the "New Testament" when Constantine, at the urging of his mother, made Christianity the official religion of the Roman Empire.

None of the "Gospels" were written in the first century. Paul's earliest letter was written in roughly 67 AD, followed by others he wrote before 100 AD, then by the writer of the Gospel of John in the first decade or two of the second century. Not the Apostle John who was imprisoned at Patmos but probably the same John who wrote the Book of Revelations. That book's meaning and the time and people it was written are entirely misunderstood, which makes for good movie material. There simply are NO "original" documents, just orally passed on stories later written on papyrus by scribes.