I'm not sure where you draw that line... should they have written the software, too? If they painted an image instead, should they have ground their own pigments and woven their own canvas? A sketch artist can't create the apples in his still life, they have to be grown by the tree. 

The poser artist may not make the model, but they do the arrangement, the lightining, select the rendering settings, commonly do their own materials, and so forth. It's usual also to modify the rendered image to perfect it with a paint program, too. My opinion would be to call the result "original work".