As a scientific construct, the concept of race is certainly problematic because it is poorly defined. However, as a social construct (somewhat like money), the concept of race does exist, and it is very real in its consequences.
A reminder would be to tell that we use the word "race" to distinguish similar carbon-based life forms based on physical characteristics. Whereas we use the word "ethnicity" to denote the belonging of a person to a social group having common traditions (national, cultural, etc)
Different groups of humans lived in different areas. Because of this separation each developed their own language and traditions. They also had different skin color. But all humans are still fundamentally the same.
The idea that one person is of a totally different variety from another because one happens to have a different skin color, or skull shape, or what have you, is a social construct that is, or rather should be, irrelevant. What matters more is cultural differences, which are infinitely more telling.