Hi @Jamie Greene,
I understand your situation, and it is indeed a desperate one. This is a "perfect storm" or "deadlock" where two critical problems have happened at the same time:
You lost Admin rights.
The Windows Recovery (WinRE) environment is broken by the recent update (the bug that stops USB keyboards/mice).
You are correct. You can't fix the WinRE bug (install updates) because you have no admin rights, and you can't get admin rights back because WinRE is broken.
I have seen this exact scenario before. When this happens, command prompt methods often fail, and the only reliable way to fix this is System Restore.
You must use an external Windows 11 Installation Media (USB drive) to bypass your PC's broken system. You will need to use a different, working PC to create this media, as you don't have admin rights.
Once you boot from the USB drive, you can access the "Repair your computer" options. From there, you can launch System Restore (which should work, as it's running from the USB) and choose a restore point from before you lost your admin rights.
I have written a step-by-step guide for this exact "deadlock" scenario on my blog, including how to create the media on another PC and the exact steps to launch System Restore.
(The article is in Japanese, please use your browser's translation feature): https://windows-waza.com/how-to-change-back-after-changing-win11-administrator-account-to-standard-user/#index_id1
Good luck! This is a complicated problem, but that guide should walk you through it.