Probably I remembered incorrectly about the specifics of Ehrman's statement. The source was a speech on youtube about the hopelessness of reconstructing the New Testament scriptures as they were originally composed.
I think not, the biggest example imo is its outlawing of the 2nd Temple era teaching of 2 powers in Heaven. Ever wonder how the Jewish disciples could accept Jesus as God without feeling they were violating Shema? Or how they could see God (Jesus) and not die? I haven't read Segal's book yet, but Dr Heiser covers the nuances seen in scripture that led to the teaching. Here's a link to the book and to Heiser discussing this early rabbinic teaching of a Godhead in the Old Testament.
Two Powers In Heaven | E-book Download Free ~ PDF
I think the earliest disciples of Jesus did not see him as God, but instead as simply the messiah and a prophet. As you stated, there is no way devout Jews could reconcile the shema and other Jewish laws and customs with the belief that Jesus was God incarnate.
They did see him as God though, that's the whole point - they were already teaching a second power of Heaven in the 2nd Temple era, so it would have been easy for the earliest disciples to conclude Jesus was this second power. Segal wrote a book on it from his research on the rabbinical teachings of that era. He views it as heretical, but admits that's what they believed and taught then.
But that second power does not equate with being the same as God. It is highly possible they believed in a subordinationism in which Jesus was a divine being, but was lesser than the father. Such a view was common and popular until the Arian Controversy.
Did you watch the video? This isn't a "lessor god", but one and the same as "the God", yet different. Same concept as the Trinity, but derived from Old Testament passages.
Edit: maybe I misunderstood your point - equal with God the Father, yet subordinated to him? Just as a human child would be subordinated to their human father, yet equal in the sense both are human? Would agree with this if I understand it correctly.
we must remember that the Hebrew Testament was largely henotheistic and it was believed for many centuries that God did not exist alone in heaven. He had not only angels but others gods or celestial beings in heaven with him and where his divine council. ... It was not until after the Babylonian captivity they became strictly monotheistic and belief in other "powers" in heaven was deemed blasphemous
These would be gods with lower-case 'g', ie spirit beings, not on the same level as God (Psalm 82:6, John 10:34). The worship of the golden calf was Israel straying from their beliefs, not acting in accordance with. But the second power was on the same level as God. According to Segal, this teaching wasn't deemed heresy until sometime in the second century AD.
Since on the topic, I just don't accept the view that early religion started polythiestic and moved gradually toward monotheism, with henotheism an evolutionary stage. I think Wilhelm Schmidt makes a compelling case for monotheism being the first belief, with his primitive high god in The Origin And Growth of Religion.