Login list is empty, yet messages, mail, etc opens upon log in...

When you log out/restart/shutdown the Mac, do you have the check in the pop-up message box for "Open windows when logging in"? If this box is checked when you logout/restart/shutdown, then the next time you log into your macOS user account all the apps & windows which were running last time will be there again.

Prevent apps and windows from reopening on Mac - Apple Support