Did YOU ALL THINK ABOUT IT???
Here i have the answer why human being different....
Physically, we are what our DNA determines us to be. My hair colour was determined when I was conceived, so was my skin- and eye-colour. Whether I would be tall or short was also determined then.
When animals mate, one half of the male's DNA is matched with one half of the female's. These halvings don't always follow the same pattern. In my case, my mother and father had four children, and each of us got different bits of their DNA.... not very different bits, just slightly different - that's why we look somewhat alike.
The reason humans differ - physically - from one another is because they all got different parts of their parents' DNA - and their parents' DNA was already different from other people's.
Most animals reproduce like this - except for insect species where there is a 'queen' who's offspring are almost all totally identical.
The other way we differ of course is temperamentally - our characters are all different because they are formed when we are young and our family background and our environment contribute to shape our personality, so we differ from people who had a very different background and lived in different times.