How did waving come about as a greeting?

many will immediately write this off as conspiracy theory, and that is okay, haha...

in the days of old, the nephilim (of reptilian ancestry, also referred to as giants in The Bible) took on the appearance of men, but preyed on mortal man. these reptilians had 6-fingered hands, and as men grew more aware of the agenda of the nephilim, they learned to wave as a way of showing one another that they only had 5 fingers, and were therefore one of their own kind.

there is a theory that it was to show that you held no weapon, but most men had two hands, so unless you waved both, this theory doesn't really hold up.