Are you saying he should have been teaching people about the universe and physics rather than theology because that would have been better proof he was a deity than anything else?
I'm just trying to figure out what the point is, not that you're incorrect in your facts. Where are we going with the facts? That teaching people about the universe would have done them more good than teaching them philosophies about universal brotherhood or human behavior?
I'm of the opinion that myth, philosophy and even religion are useful knowledge, for no other reason than our culture and society are based on them if nothing else, they are as important as physics or other sciences, which I also find useful, of course. I can't really say that Christ teaching people advanced physics would have done them good as a society...what would they have done with it without accompanying technology, which is why technology and concepts tend to come together. One supports and influences the other.
I don't think Jesus of Nazereth had access to that knowledge and technology even available then, being a man born of that time and of average means, apparently, so how could he teach people things that a man in that situation would have no knowledge of?
I'm not particularly convinced that Christ was a deity in the flesh, but I do think he was a great spiritual leader and teacher.
When you say "Teach them" I'm reminded of a story about some friends of mine who went to Africa in the Peace Corps back in the 60s.
They went to a village which was still quite primitive, and were trying to teach the local men and women about birth control, and were demonstrating using condoms by placing them over the end of a pole, which was the only way they could think of demonstrating it without using an actual erect penis.
Thinking they'd really done a good job of showing how condoms prevent pregnancy, they went on to the next village and so on and so on and made a circuit until they came back about six months later to the original village. When they got there, there were poles placed all around the village outside of some of the huts with condoms on them.
Since the people really didn't have the concept that it was the invisible sperm in a man's semen that joins with an egg inside the woman's body that creates fertilization and results in pregnancy, they assumed that the nice white people were demonstrating some sort of anti fertility ritual and thought placing condoms on the ends of poles outside of their huts would prevent pregnancy.
Anything we don't really understand becomes magic. Even if it works, we still think it's magic unless we have the underlying information to know why something works.
It was easier for these people, with no technology or scientific knowledge of human reproductive biology (I'm sure they had a working knowledge of pregnancy and childbirth from what is observable without technology), even when it was explained to them, to believe it was a magical ritual they were being shown. They weren't stupid...they just didn't have the underlying concepts.
So, getting them to understand why and how the condom worked would have literally taken the Peace Corps people YEARS of education and by then, the village would have still been suffering from too many children and not enough food.
So, they simply decided to go with the current state of knowledge and told the people that they needed to put the magic condoms on a man's actual penis to work.
Problem solved. I'm sure that they got to work on educating the people about how condoms really work, eventually, but in the meantime...
So, even if a man with advanced knowledge comes along....how long would it take to get everyone up to speed, even if they believed what he was talking about? Would it be easier just to go with the current state of knowledge or try to bring it up about 200 centuries in a few years?