We all belong to the same biological species, or as we say in more humanistic terms, we are all members of the same large human family; biologically speaking, we are all descendents of the same great apes. Yet, an important aspect of the human condition is that, over the eons, due to various historical and cultural reasons, we have divided ourselves into countless groups and subgroups.
These sets and subsets of humanity are not unlike children: sometimes they are mutually cooperative, sometimes mutually indifferent, and sometimes mutually combative. The major factors that unite and divide us are race, religion, and language.
Race is no longer an acceptable term, either scientifically or in terms of political correctness. One prefers the less noxious term ethnicity. Be that as it may there still lingers in human beings differences in skin pigmentation and to an extent, even in facial features.
Religion has been a mighty force in human history, and is still so in human culture. It has both noble and ignoble sides. It teaches us that we are all children of the same Divine principle, that the same God molded us all. Yet, there have been at least as many ugly confrontations due to religious beliefs as due to greed and thirst for power over other people.
Language is beautiful and endearing to those who understand it. Every language is like a different musical instrument, and every poet is a virtuoso who wields her language with ease and creativity. Yet, foreign languages throw people into states of bewilderment, incomprehension, and sometimes even distrust. These three factors also form the basic elements of human culture. Culture is situated in Nature.
The world of nature strikes us by the plethora of elements which range from stones and sand particles to living organisms and stars and galaxies. All these are situated in the Cosmos. All this variety contributes to the aesthetic splendor of the world that touches us all. We have no inkling as to why it is all so beautiful. Through cosmology, astrophysics, geology, and biology, through physics and science more generally, we have come to understand how such variety came into existence, but not why. Perhaps, the variety in the world, whether in the biological and human context, or in the physical and astronomical realm, is a necessary condition for a universe to exist as a stable complex entity.