Well, actually you will find this parallel to Christianity because the ancients were aware that salvation was to come to mankind through God's plan of salvation. Until God revealed His plan specifically to Abraham, many nations had coveted it for their own glory, and used what they knew of it for their own beliefs. Just like the Spanish found a bizarre religion that looked superficially like Christianity in South America, what these people practiced was a counterfeit of the true plan.
So do you think that God originally spoke to all groups of man, but evnetually most of them drifter away from God, but Abraham stayed loyal?