The story of the resurrection of Christ is recorded in all four Canonical Gospels and is one of the most important aspects of Christian Faith.
Actually, the kerygma part of the story about Jesus has a singular origin because the three later gospel stories are embellished copies of the oldest one, the gospel of Mark (gMark).
Hugh M. Humphrey explains in his book 'From Q to "Secret" Mark, A Composition History of the Earliest Narrative Gospel' how he thinks that gMark was probably or possibly written in two stages by Mark, the first bishop of Alexandria.
In the first stage he wrote about the travels and miracles and teachings of Jesus partly based on Q (the oldest sayings of Jesus gospel). Somewhat later he added the second part, the kerygma story which shifted the emphasis from Jesus the Master or Teacher towards the resurrected godman or Christ.
The kerygma part is clearly fiction (e.g. a scene is described with Jesus speaking things in prayer in a garden setting with no-one else present).
The author joined the two quite different halves of the story quite simply by making Jesus predict the kerygma part on several occasions during his teaching phase.
The kerygma to me has a very fictional feel, but I cannot rule out that the mission did end in such a type of tragedy, unless Jesus himself was totally fictional or mythical.
Otherwise it is hard to explain how the mission of Jesus came to such an abrupt end and why it lasted so short. The teachings of Jesus don't seem to be at all properly understood by the authors of the gospel stories which would fit well with a very short mission and a sudden disappearance of its master or guru.
The followers then picked up the meager pieces and still heavily impressed by the powers of and love of/for their master concocted a syncretic religion which would take the form of Christianity.
The idea of the kerygma was a fictional one possibly based on other such forms of worship in the Hellenistic culture.
It must have started in a small group of followers at a very early stage.
If it was entirely fictional then where did it develop?
Did the Ebionites already see Jesus in this way?