I came across this sermon today, by Mark Bernstein of the UU church. In it, he discusses his own and Campbell's insights into meaning that is common across all religious symbolism. I thought it might be of interest to some here at RF.
http://www.usguu.org/documents/Joseph_Campbell_sermon_copy.pdf
http://www.usguu.org/documents/Joseph_Campbell_sermon_copy.pdf
All myths, all religions speak to the same reality and convey the same message. The stories differ because a different language was needed to speak to each time and culture. The message is how to live in this world.
Only two things could explain the commonalities: dispersion from a single source, or independent creation by diverse peoples emerging from common human experience, emanating from the same human psyche, which is in fact connected with a transcendent reality.