500 error on my main site in multisite, but subsites are fine

Happy Thursday!
Summary: I am getting a 500 error on the primary domain of my WP multisite installation at esmiths.net, and cannot access either the wp-admin for that site, or the network admin. However, all of my subsites, which have mapped domains, are fine both on the front end and I can access their wp-admin as well.

The error log only repeats this, but I can't figure out what it means:
PHP Fatal error: Cannot redeclare get_cli_args() (previously declared in /home/esmithsn/public_html/wp-admin/includes/class-wp-importer.php:275) in /home/esmithsn/public_html/wp-admin/includes/class-wp-importer.php on line 323

LONG STORY: I tried to set up a wildcard subdomain...

I recently switch hosts, but forgot about setting up a wildcard subdomain since all my subsites have mapped domains. In the process of troubleshooting some random, but otherwise inconsequential behaviors, I realized that setting up the wildcard subdomain might help.

I wasn't able to set up the wildcard subdomain in my cPanel, because of an error that read "That directory is reserved for use by the system", so I wrote to the host support for help.

They wrote me back that they set it up for me, but as soon as I went to log in to wp-admin, I got only a 500 error. Same on the front-end site.

Literally, the wildcard subdomain is the only thing that changed in the minutes between me being able to access my site, and the 500 error.

When I replied back to the host support, they sent me a copy of the above mentioned PHP error and said it was a Wordpress problem.

I removed the wildcard subdomain record so I could at least go back to the way things were before, and it appears to be gone (with the brief appearance of this strange error: There was a problem removing the subdomain “*.esmiths.net”.
Failed to find the domain(s): “*.esmiths.net”. at /usr/local/cpanel/Cpanel/PHP/Config.pm line 255. Cpanel::stuck_out_tongue:HP::Config::_get_php_config_for_domains(0, ARRAY(0x20a2a98)) called at /usr/local/cpanel/Cpanel/PHP/Config.pm line 275 Cpanel::stuck_out_tongue:HP::Config::get_php_config_for_domains(ARRAY(0x20a2a98)) called at /usr/local/cpanel/Cpanel/PHPFPM.pm line 877 Cpanel::stuck_out_tongue:HPFPM::_removedomain("*.esmiths.net":wink: called at /usr/local/cpanel/Cpanel/Sub.pm line 544 Cpanel::Sub::delsubdomain(__CPANEL_HIDDEN__, __CPANEL_HIDDEN__, __CPANEL_HIDDEN__, __CPANEL_HIDDEN__, __CPANEL_HIDDEN__, __CPANEL_HIDDEN__, __CPANEL_HIDDEN__, 0, ...) called at bin/admin/Cpanel/domain.pl line 227 bin::admin::Cpanel::domain::__ANON__() called at /usr/local/cpanel/3rdparty/perl/526/lib64/perl5/cpanel_lib/Try/Tiny.pm line 95 eval {...} called at /usr/local/cpanel/3rdparty/perl/526/lib64/perl5/cpanel_lib/Try/Tiny.pm line 90 Try::Tiny::try(CODE(0x208ca50), Try::Tiny::Catch=REF(0x124c030)) called at bin/admin/Cpanel/domain.pl line 231 bin::admin::Cpanel::domain::script("bin::admin::Cpanel::domain":wink: called at bin/admin/Cpanel/domain.pl line 41)

But I'm still getting the 500 error, and the error log is still recording the same PHP error as mentioned above, and I'm totally lost on what to try next...

Any ideas?
Thank you!
-Melissa