While "Calvin and Hobbes" can be seen as a form of storytelling, Watterson considered himself a cartoonist and not a writer. He believed that the art of cartooning encompassed more than just writing and that his primary focus was on the visual aspect of his work.
It's worth noting that Watterson was very deliberate about his artistic choices. He refused to license "Calvin and Hobbes" for merchandise or adaptations, wanting to maintain complete control over his characters and their message.
So, while he wasn't an author in the traditional sense, Bill Watterson certainly used his artistic abilities to tell captivating stories through the medium of cartoons. He achieved this by using humor, philosophy, and visual storytelling in a way that resonated deeply with readers and continues to do so today.