In the strange and wondrous world of Dr. Seuss, we human readers need some part of the story to feel human. It helps us attach ourselves emotionally to the zany-crazy happenings. And in The Sneetches and Other Stories, the titles tell us where exactly in the story we are going to find those heartstrings.
Examples? In "The Sneetches" and "The Zax," we are the Sneetches and the Zax. Their vices are our vices, their successes ones we hope to accomplish, and their failures ones we hope to avoid. Sure, they are funny bird and grumpy dog creatures, but their essence is a human one.
Now read on, and become one with the Sneetches. And other stories.