That premise doesn't make any sense. If humanity had no knowledge would they know the difference between religions they have no knowledge of?
Mythologies often reflect the way of thinking in the world at the current time and how the collective whole interpret and understand the world. As our way of thinking changes, so do mythologies. The only constant is we're never fully right yet always assume we are, and more so, we assume we're more right than we were the day before in almost all things. We ignore our current biases and edit the past to accommodate our current way of understanding.
Honestly, when I see people rant about religion as if it has never been necessary, all i can think of is all the foolish egotistic patterns of the past.
