In my classroom I would never let my students copy someone else's work. If it was copyrighted it was off limits. Coming up with new ideas is daunting. Our society is drifting away from creativity and I think it has to do with accepting the copying mentality. We see paint nights where everyone paints the same picture. That is ok for a little entertainment but we must go past copying and begin creation. Copying is for learning a technique. Art must be more than technique. Art must have elements of self expression. A "little bit of you" has to be in the art. It is the reason we love the great artists. Their personality and creativity is all over the canvas.
Don't copy cartoon characters... create your own.
Don't copy a landscape ... go outside and observe and then paint a landscape.
Don't copy someone else's ideas and thoughts... create your own.
It is o.k to be inspired by someone's words and art.... but you have to be inspired to create new ideas and art.
Add and subtract and make it better.
Give credit where credit is due.
You are creative. You have to use it.