Yeah, if the common wisdom was that the rock slowed as it fell off the cliff. What I'm trying to illustrate is, the Golden Rule is not very surprising. By the time most people have grown up into mature adults, some form of the Golden Rule is understood to be obviously true. So when an adult starts preaching the Golden Rule and then says, "oh, by the way, I'm God," the fact that he's preaching the Golden Rule is hardly evidence of his superhuman intellect & wisdom.
But it is. Consider the Old Testament Code of eye for an eye. Consider the Roman code of the 12 Tablets.
"Do unto others as you'd have them do unto you" is revolutionary.