crimson Yes, I did watch that series about how much light there was in the "dark ages" It was fascinating, not least about the amount contributed by Islam and the Norse legends.
The images of the early church were of Christ coming physically in majesty to rescue mankind. At that time they believed that the end of the known world and the final judgement were imminent, so they were working tirelessly to convert and save as many people as they could. The Christ they needed was a charismatic leader who would take them forward in a political way as well as a spiritual one. The artistic models were the classical statues of Greece and Rome.
It was when time went by with no cataclysmic second coming, but plenty of trouble and persecution from the establishment, who did not want to be abolished in favour of some provincial (and supposedly dead) preacher, that the emphasis changed to a spiritual leader who would change the inner life, not the outer one, and set an example of self-sacrifice.