There has been a critical error on this website.

If you can’t access the email the only way in is to change the email address. In your situation, the only way to do this is by editing the wordpress database. If you are uncomfortable doing this it is best to contact your web host. If you want to do it yourself see step three here: https://www.wpbeginner.com/beginners-guide/how-to-change-the-wordpress-admin-email/

Please backup your site before editing the database as it can seriously break your site

Of course an admin email address is not causing a critical error but if email is not one of the OPs problems then what else could “i cannot access the email linked to this account anymore” mean? Have I munsunderstood something?

Yes sir. Understood sir.

Can I humbly suggest to the commander that they consider that for someone that explicitly asked for “layman terms”, a single challenging technical step of changing the admin email might provide access to the WordPress dashboard, could provide a much more user friendly way to disable plugins and troubleshoot than expecting them to be able to understand error logs, edit core files and renaming folders on a server?

So to the OP, you have a few options. If you manage to change your email and get access that way you can then start to troubleshoot through your dashboard. Here is a user firendly guide: https://kinsta.com/knowledgebase/there-has-been-a-critical-error-on-your-website/