Human culture is very diverse. It is it's key property, so it is reflected in everything - number of languages in which humans write poems and sing songs; different styles used in architecture of different human nations; thousands of various articles of trade and works of art brought from all ends of the world to Empire's markets. Human life is short, so they hurry to live and, sometimes, they during two years can do much more than representative of other race during a dozen of years. They hurry to have fun and amuse themselves, they don't know temperance in their desires, they often make mistakes, and never learn by their own mistakes - but majority of them live full and rich life.
Humans learn easily and easily get accustomed to representatives of other races... one can meet orcs, gnomes and elves on the streets of human cities. Human culture has many adoptions from other cultures - elven language and orcish martial art, technologies of gnomes and goblins, elven poetry and magic - this is not full list of what humans studied during last one and a half thousand years.
Human cities - are boiling up kettles, great works of art and horrible crimes are born there; life adjoin death there, beauty adjoin ugliness - they are as changeable and inconstant as humans are. Arcspire - is the biggest city, capital of Empire, city of hundred gates and thousand castles - center of human world.