Why might art spiegelman have used animals instead of humans as characters? wha
do the mice represent, or symbolize?

Spiegelman uses different animals to represent different people groups. For example, mice represent the Jews. They are the helpless, vulnerable victims of the Nazis, who are represented by cats, because cats and mice are, of course, natural enemies.

"the sandy walls seemed to collapse in on themselves"

and

"the bloodshot waters seemed to have no bottom"