Americans value sincerity and authenticity due to their religious inheritance. Your politicians, for instance, never tire of invoking God.
But there is a disconnect because American keep telling us they have the best sense of humour in the world, yet to us, Americans seem humourless. I know this is hard to believe but it is true.
Americans come across as religious but humourless, and this is just what we would expect from a religious country, deep in a religious trance.