Yes indeed there is clear evidence for this. The plain written words of God tell us so.
A later interpretation and should not be confused with
Theotokos.
Debatable. As John received that mission personally.
Glad you mentioned this. I guess the early church 'forgot' a lot about Marian devotion as it was absent for the first 500 years of the church.
I will use only Catholic sources:
From then Cardinal Ratzinger (better known to all as Benedict XVI):
Before Mary's bodily Assumption into heaven was defined, all theological faculties in the world were consulted for their opinion. Our teachers' answer was emphatically negative . What here became evident was the one-sidedness, not only of the historical, but of the historicist method in theology. “Tradition” was identified with what could be proved on the basis of texts. Altaner , the patrologist from Wurzburg…had proven in a scientifically persuasive manner that the doctrine of Mary’s bodily Assumption into heaven was unknown before the 5C ; this doctrine, therefore, he argued, could not belong to the “apostolic tradition. And this was his conclusion, which my teachers at Munich shared .
This argument is compelling if you understand “tradition” strictly as the handing down of fixed formulas and texts…But if you conceive of “tradition” as the living process whereby the Holy Spirit introduces us to the fullness of truth and teaches us how to understand what previously we could still not grasp (cf. Jn 16:12-13), then subsequent “remembering” (cf. Jn 16:4, for instance) can come to recognize what it has not caught sight of previously and was already handed down [invisibly, without evidence] in the original Word,” — J. Ratzinger, Milestones (Ignatius, n.d.), 58-59.
Basically Ratzinger is telling us the Church forgot this most important doctrine but remembered it much later. Even though, as he admits, there was no historical evidence prior to the 5th Century AD. Which he does not try to defend from a position of Holy Scriptures at all.
Therefore, your argument among other RCs here is the same as Karl Keating:
"The mere fact that the Church teaches the doctrine of the Assumption as definitely true is a guarantee that it is true.” — Karl Keating, Catholicism and Fundamentalism (San Francisco: Ignatius, 1988), p. 275.
Which is a circular argument.
However, not surprising as indicated here as well:
"It follows that the Church is essentially an unequal society, that is, a society comprising two categories of per sons, the Pastors and the flock...the one duty of the multitude is to allow themselves to be led, and, like a docile flock, to follow the Pastors" (Vehementer Nos, an Encyclical of Pope Pius X, 1906)