Nothing in dashboard that uses javascript works

I cannot see the media I have uploaded under the Media Library–it’s a blank space(though I can upload with the html uploader ).

I cannot use the Select All checkbox to select all the plugins on the Plugins page. (I have to do them one at a time)

I cannot set a page or post to Draft.

In short, if it needs javascript, it doesn’t work.

I have disabled ALL the plugins AND used a default theme (at the same time).

I have tried to install a few security plugins, but they all seem to use javascript. I have however run a few online scans and no malware turns up.

I was editing some images the day before, and it was working fine.

I don’t know what else to do besides build the site back up from scratch.

I am running PHP 7.3.24 WordPress 5.5.3 (the latest I believe)

Any ideas?

Edited to add that I have entirely replaced the wp-includes and the wp-admin folders. Also note that the site otherwise seems to work perfectly