Well I'm not real good at this stuff but I will take a stab. This is a hard question and I don't think anyone has all the answers, but here is my opinion. I'm going to jump around a bit so hang with me and hopefully this makes some sense.
First thing everybody came from the same natural life more or less, the only difference is environment and development. A bronze age settlement on Salisbury Planes would be just as natural as an Apache tribe on the Western plains. Not only would these people groups both be similar in dependence on nature they would also have a pretty similar lifestyle. How and why they developed differently is beyond me, but is somewhat dependant on a nomadic people and a agrarian society (Sorry off topic a bit). In a nutshell the natural peoples your talking about are really similar to the societies of today, just add time, environment and development. (Some Sociologist is going to nail me on this)
Back in the beginning Man had a perfect relationship with God and nature however man screwed it up. Once sin entered the world the whole order of things was messed up, we are talking about the worst disaster ever. God cursed the ground so that man should be in a constant fight for his crops (growing up on a farm I can attest to that) From this point onward history is full of people trying to into Gods good grace by works, worship, and sacrifice. To face facts the human race is prone to commit some pretty horrible acts in the pursuit of God, fame, power and fortune. God sent his son Jesus to save the world by his sacrifice on the cross. Jesus died after only three years of preaching, not a long time. There was no internet, Tv, radio, etc, however Jesus made a huge impact globally. Jesus gave some very specific commands to his followers one of which was the great commission. Those who follow Jesus are called to preach his message to the whole world. Christians have faced death and violence in order to bring this message to all people groups. Even today a Christian is more likely to face martyrdom (Death for their faith) today then ever before. The lack of Christian representation is really Christians failing to fulfill our obligations.
To back up a bit the first Christians did not have a Bible, fancy universities or degrees in ministry (Not that these are bad things) they were people who Jesus said "worshiped in spirit and truth" These people believed that Jesus was the son of God and died for their sin. They died to their old life and started a new one following Jesus as an example of how to live (Nutshell stuff). So the message of Jesus can be pretty simple.
Tough question Jeremiah I hope I have at least given some things to consider about your question.
Brad, there are a some very interesting points of view in your contribution.
In fact I have, over the years, my question reconsidered many times and yes, the message might be pretty simple.
Buddhism theologically not defined as a religion, it is a way of live.And it says the same: everything is pretty simple, do not search to far, the "key" is right next to it.
So I think I see the guiding lines, the similarities, giving the trace of an idea what God is really all about:
not a Religion it is a way of live, a way to live, a super-ultra- fine connection, like an over dimensional energy net all over the whole world, through time, space and infinity....
It finds in Buddhism its most simplest explanation, pretty simple as Jesus and Mitra(s) were born at the same date, as the Islam is right, that it is for Man not possible to create a picture of God because of his divinity...as the Islam is wrong to prohibit this challenge to an artist...
so this even eliminates "the first sin of man " i will not call it an apple, nor will blame women to bring men into temptation, as far as it goes in history, men never had to be pushed, or forced to do the "Sin", the male part was the first sinner if! there is one first sin and here it goes on and on....
I see one evidence after another that it is all the same and so subtle and distinctive, it is All, One, Him and The Same.
No one can imagine divinity.
we have not the potential to use 100% of our brain....as far as I know it is about 10% with humans and with Dolphins it is about 20%( tell me please if I am wrong).
To me, The Word of God comes to a complete new interpretation.It makes sense to me that it is The Will of God , to look as his words from as many different points of views as possible....that cannot be so much with 10%....so to me there is another one:
The Patience of God must be endless like space.
Thanks for Your contribution Brad, I appreciate it very much!