Sameness is where everybody is exactly the same. Nobody is unique, but also nobody has a choice. It protects people from making bad choices, but it also means that you can never decide anything for yourself. Your life is already preplanned for you. Lack of choice makes life predictable and boring because life is about making choices, and being spontaneous, and also just living. But sameness doesn't allow people to do that.
The author draws the connection between Ancient Greek mythology and modern western society. They do this by stating that Greeks created gods in the image of humans, and also with the same traits/ humans qualities.