Superstition and credulity in antiquity
People back then were extremely superstitious. If I strolled into the town square and declared that a god had come to me in a vision the previous night and declared that a famine would sweep the land in 5 years, they'd all begin stockpiling food and provisions.
My famine prophecy example indeed recalls Acts 11:27–30, where Agabus predicts a famine by the Spirit ... exactly the kind of claim my scenario describes. Ancient people often trusted prophets, dreams, and omens. As Robert Garland (The Eye of the Beholder: Deformity and Disability in the Graeco-Roman World) and Robin Lane Fox (Pagans and Christians) both note, visions, portents, and divination were woven into daily life.
I hold a personal view that Paul -- who never saw Jesus except in visions -- began preaching in the 50's CE and gained a following. I believe that Mark wrote a back story (fan fiction?) which was picked up by Matthew, who corrected Mark's inaccuracies and geographical mistakes and quote mined the Old Testament, then Luke who expounded the story even further. Finally John decided to turn Jesus into the "Superman" of the era. When I examine how Paul's letters evolved against the backdrop of how the Gospels themselves evolved, this seems to my way of thinking to be a plausible explanation.
So my model - visions → literary backstory → successive elaboration - does fit a recognized scholarly trajectory. The only real dispute is how much history lies behind it. Some (e.g., G.A. Wells, Carrier) say “none.” Others (e.g., Ehrman, Sanders) say “a little, but overwhelmed by myth.”
We cannot ignore the influence of myth, superstition, previous writings (e.g. Homer), nor can we ignore the willingness of any religion to vociferously work to stamp out anything it regards as heretical along the way. Indeed, the ONLY knowledge we have of some religions, like Basilideans, Marconites, Valentinians, Sethians, Ebionites, Mithraism, etc comes from Christian polemics (e.g., Justin Martyr, Tertullian), who accused these of heresies ... although the Nag Hammadi texts have been found since 1947 among the Dead Sea Scrolls and we're learning what all the Christians hated in their communities.