In all likelihood Christianity started as a sect within Judaism.
Yes and no.
You need to be more specific.
Jesus was a jew, who taught Judaism native to his geographic location.
That movement died, with his death.
Jesus death however was martyred, and the people that found importance in his death were not typical Jews, but Proselyte Hellenist who wanted to worship one god, but did everything possible to not be labeled a Jew.
They avoided Judaism at different levels depending on which community was doing the worshipping. GMarks community not so much, while Gmatthews community wanted to hold Judaism a little closer.
And there were arguments about how close Judaism should be held. Thus we have Pauls epistles from his community.
As this sect departed from the time and place of its origin it became more and more unlike Judaism.
Dead wrong.
As these multiple sects everywhere began to grow, they were already far removed from Judaism as they were never born and raised oppressed Jews. They were Proselytes and Gentiles who were never fully Jewish to begin with.
Since this new sect did not gain wide appeal from the majority of Jews
There was no majority. This is a misunderstanding of first century Judaism, that was very divided and diverse with 4 major sects, all with different views.
, the original beliefs may have changed to accommodate the influx of Gentiles.
No
The mythology grew, and gentiles found importance in it.
Logic would dictate, the more something changes, the more its unlike its original form.
Yes the movement evolved as mythology grew.
It is because of the rejection of Pauls message, Paul went to the Gentiles.
This is a complete misunderstanding of everything associated with early Christianity.
It not only makes no sense, it just did not happen that way.