I have been trying to place my hands on how some form of greetings came about.

One of such is "How was your night? To me, its like an invasion of my privacy. Why do you want to know how my night was? When people ask me how my night was, I just reply okay because you certainly do not expect me to go into any details

If I was being intimate with my wife, would I tell you? If I was having a sweet dream or nightmare, would I tell you as well?

I think this form of greeting has no meaning. Just my opinion anyway, others' views are welcomed.