Are Races Real?

No and yes.  Biologically, they are not very real, since the variations we see between so-called races are small compared to those within any of them.  However, as social constructs, they can be very real, strongly influencing the ways people interact with each other and how they view themselves.  

Social constructs (including money, nations, corporations, etc.) have tremendous influence on our lives, but they also are pretty ephemeral compared to biological realities.  Of course there are real differences among people that are correlated with ancestry.  Some time after leaving Africa, most Eurasians developed lighter colored skin, which seems to be adaptive in climates where sunlight is in short supply.  Most of these differences are as superficial as the melanin proportion in our skin cells.

Since those who first developed racial theories were light skinned, it was not coincidental that they picked skin color as a defining characteristic, and their own type as the highest.    Who got to be defined as "white" has varied a lot over time.  Among those getting the non-white designation have been Jews, Italians, Greeks, and, amusingly enough, the very light skinned Irish.

Humans evolved to compete in groups against other groups, so we are very good at defining the other.  Accent, skin color, or even the color of the baseball cap you wear can be the dividing line.  It is one of the things that makes creating just civilizations challenging.