One of the best ways to understand anything, whether it's tangible or simply intellectual, is to define how it is like you and how it is not. A rock is like you, because it exists on the earth, grows old with time, is subject to various natural disasters and is made up of tiny atoms and quantum energy. A rock is not like you, because it has no mouth, ears, organs or limbs, and as best anyone can tell, rocks don't have any 'human' motivations, even if it could be proven that rocks might have some form of intelligence.
And through that little story, I hope it's easy to tell why we humans Anthropomorphize things. The best way to explain something to anyone else, is to show them how it is like them, because we are experts at knowing ourselves. =P