It was not a group of Jews who fabricated the Mithraic version of Jesus, mostly these were Pagans/Gentiles, churches Paul had started, not the Super Apostles.

NONE of the founders of the Roman Catholic Church were Jews.

Pagan Christians (non-Jews) had everything to gain from a Mithras-like story in the first through 4th centuries since is was basically a rebranding of the very popular Mithras story that was already popular in Antioch and Rome.

Jewish zealots didn't see Jesus as a messiah. Your perspective is flawed by man-made tradition getting in the way of a true Hebraic period perspective.