This question seems to have many answers. Some people agree that we are all one, yet from a physical point of view we appear to be quite different. Our upbringing defines us as human beings and makes that we appear and behave so differently, mainly due to the set of believes or values that are part of our education, or the lack of it.
How well do you know, or are you aware of your fellow human beings around the world? This trilogy gives us a glimpse into the lives of a very wide selection of people. They answer questions like: what is love, or when would you be happy? I found it staggering to discover the sheer difference between the answers of a citizen from a western 'developed' country like the United States and a poor farmer from Kazakstan.
One of the most intriguing things for me was that these films altered my frame of reference and that I felt connected to all these people. The framing is very intimate and they answer to very personal questions. All of a sudden the refugee, the poor farmer and the factory worker from Bangladesh have a face. This allows you to connect to subjects that are easily considered out of your reach, because they are touched upon by people of flesh and blood.
It's quite an experience, I would call these films life enhancing, so enjoy the ride :-)