I’ve talked about it in the Five i’s of Creativity, but you really should know that most art draws on and builds on art created before. Here’s an example that I found over at Tested.com
The art is not in the originality of every concept, but in which concepts you choose and how you impliment them. Notice that while iOS 7 is a lot like Android and Windows Phone, no one mistakes one for the other. Like isn’t exactly the same. Cars are like one another, but a Mustang is a Mustang, not a Silverado. Understand?