Thanks Leo,
This issue was caused by the sketchy hosting environment provided by BlueHost. While diagnosing the multiple issues, I encountered a “phantom” WordPress installation and database when there should not have been one. I fixed the multiple problems by deleting everything and starting over. Once I had a clean hosting environment and a fresh new database, I uploaded my Duplicator Pro installer script and the zipped website from my staging server. Everything ran and installed perfectly, and all the problems were gone.
This was a BlueHost issue, caused by BlueHost. In 4 online chat sessions with their support staff, none were able to identify and correct the problems. One of them apparently went into the site and installed the Classic Editor into an all Gutenberg website! I had not done a BlueHost installation in over a year. I discovered that their already iffy support has gotten worse. Now, they are just another once solid hosting company made mediocre by EIG.