The "all all all" report in cPanel's IP blocker does imply that everyone is blocked from accessing your site! However, that does not seem to be the case. I would assume that cPanel's "reporting" is perhaps in error, or rather "not entirely clear" (see below).
cPanel blocks IP addresses by simply creating the appropriate
allow from ... and
deny from ... directives in the root .htaccess file. Likewise, it reports the blocking "state" by scanning this file.
How can I recreate this "All" rule?
You can manually create a
deny from all rule in .htaccess and cPanel will report this "All" rule. I don't think you can create this in cPanel as "all" is obviously not a valid IP address.
See if you can see something similar in your .htaccess file. It might be conditional! For example, I have found that the following is enough to trigger this "All" state being reported:
deny from all
This obviously does not block your entire site, however, it does block all users! cPanel's reporting is not entirely clear since it does not differentiate.