You got to hand it to Noah for building an ark...that was an original. Not only had nothing like that been done before, but he had no architects to consult or weathermen to double check God's prediction (if you can call anything God says is a prediction).
Joshua received a battle plan that was pretty original as well. Who would EVER think up something like that? "OK, for this battle, let's not use swords. I think trumpets would be a much better weapon."
Abraham, who came from a non-religious family, followed God away from safety, security and wealth into obscurity and the unknown.
I think God sets it up this way so that there's no doubt where the credit goes. When faith is involved there is rarely a clear path or a proven method to go along with what God has called you to do. This is one of the many reasons why I am glad to be a part of a movement (Newfrontiers) whose founder (Terry Virgo) has gone down "No Well Worn Paths". It's easy to trust a man who trusting God.
When God presents to you His call for your life, do not expect to imitate what has been done before, but prepare yourself for something new.