While Game of Thrones / ASOIAF have many separate interconnected stories and might indeed simply have multiple circles, one for each point of view character*, there are many stories that have a cast of characters and no protagonist.

For example, you could, in principle, analyze the story of each individual character in the Iliad, but that would be missing the story. The story of the Iliad encompasses all of these different characters doing to their part to advance or retard their cause. Different characters are more important in different parts, but there is a single cohesive story being told.

* though even here I would say that the stories of many of the characters don't match the circle model - notably, Ned doesn't return to anything.