I don't think that you can conclude such things, because we have insufficient reliable information about the true beginnings of the mission that Jesus supposedly started. What we do have is mere Christian story telling about how it may have started. The sayings in Q-lite are not specifically Jewish nor are they in any sense Christian. They are universal spiritual or mystic teachings which also seem to include a devotion for the spiritual Master (Jesus as one with God), which is certainly quite different from main stream Judaism.Which raises the question did Jesus intend to establish a new church, a new religion or was his intent to renew his own within its established form of worship much of which was retained by the church. Not until Christians were expelled from the Temple did Christianity become a religion wholly separated from Judaism.
As for what you term as 'fabrication' it is necessary to distinguish what is myth, legend, folklore, (narrative) from the confession of faith the core of which is received and handed on through generations. Or maybe you would prefer the heretic Marcion and a NT with only Paul and Luke?
I would prefer just the reconstructed text of Q-lite and nothing else as historically certain. I don't believe most of it was 'handed on through generations', nor do I believe in the apostolic myth. Most of it is fabricated religious myth, story telling to inspire people into the "correct" Christian faith which of course went through a complicated development in the first two centuries.
Marcion comes at a point in time when the orthodox version of the Bible had not yet christalised, his Church was not a heresy but simply an early type of Christian Church that rejected the more Jewish lense on the faith as well as the hybrid compromise that the orthodoxy in Rome was trying to promote. After orthodoxy had surpressed most of the earlier Church forms, the Marcionite Church became futher demonised as heretical and the lie was spread that Marcion had shortened the gospel of Luke and the letters of Paul instead of the other way round (orthodoxy altering Luke and the letters later on). By carefully studying the anti-heretical books about Marcion you can prove how they tried to twist the truth around to make it seem that Marcion had changed the texts instead of earlier orthodoxy changing the texts that Marcion used.