Update: Purely by accident, I scrolled down to the very bottom of the WPBakery page editor and found the options for Revolution slider, including the ability to disable displaying it. I disabled it and created a new content area where it would logically go on the page and was able to add my hero image.

But that still doesn’t explain why the content area where it is displayed doesn’t show up in the WPBakery site map/flowchart for that page. It’s very confusing.