Defining Race and Ethnicity

After thoroughly reading the textbook Understanding Race and Ethnicity, I came to the conclusion of what is considered to be my most emphatic definition of the word race. Simply put, I considered myself part of the “human race”.
There are obvious cultural differences between us in the states. However, I find that to be our strongest asset. Our diversification, along with our collective knowledge acting as one.  
How did we as complex, multi talented, human beings get to this point in our history where this classification of race, still plays in the “psyche and social fabric” of our time period? I am not naive to realize that some people delve into the subject to justify their own insignificant shortcomings, or maybe just to feel “superior” over another ethnic group.
However, in the grand scheme, it’s nothing more than a vague illusion to think that all of our lives are “not” somewhat intertwined together in one form or another. Each one of us has our own “unique” ethnicity that allows us to seek out and align with other humans with a similar background or experience. This allows “instant” connection and synergy.
My example of that would be from my personal experience when I attended a predominately white college in Alabama, and meeting across the room, someone with a similar ethnic background and experience which helps with my “instant” connection. At that moment, I did not feel alone.
Throughout the history of United States, different ethnic cultures have contributed a great deal of time, labor and love for the construction of this republic. Although most people on the outside of the country would consider the United States a racial experiment declining in its last days. The issue of race is extremely important to the United States because there is no other place in the world like us. We proceed with tolerance and inclusion, or to be left open for the rest of the world to constantly point out our hypocrisy in dealing with the matter of race peacefully.