How can I restore missing DLLs / fix windows update failing to retrieve updates

I'm working with windows 10 on a laptop I've had for several years. For the better part of a year now, I've been struggling to get several windows updates to download to my computer. The updates that are failing to come through are:

As in the image, these seem to be stuck at 0% forever. Occasionally, one or two of them will fail with the hex code 0x80d02002, with the option to retry, but I get stuck in the same loop.

In my attempt to fix this, I've tried several things, I'll list as many as I can remember below:

• restarting my computer (duh)
• running virus scans
• clicking "retry" several times (I read that it's possible to get the hex code above if the updates you're trying to download are too big to be retrieved in one download attempt, but if you retry a bunch it will download the update in chunks, but that doesn't seem to be working)
• running the windows update troubleshooter (it tries a couple things, then says that it couldn't find a problem)
• downloading the latest cumulative update from microsoft and running that installer (after the installation finishes, the same updates are listed as available and still don't download)
• pausing and unpausing windows update / restarting the windows update service
• checking for system file errors with "DISM.exe /Online /Cleanup-image /Restorehealth" and "sfc /scannow" (sometimes, sfc reports that it found and fixed some violations, but that doesn't seem to fix the issue at hand"
• booting in a safe mode and attempting the updates in that environment
• stopping the update services, emptying out the /SoftwareDistribution/ folder, and restarting the services (often, windows claims that it can't delete some files because they are being used by another process, but sometimes it has let me delete everything and this hasn't fixed the issue)
• resetting windows with "Reset this PC" -> "Keep my files" (I do want to keep my files :) )
• following the instructions here: https://docs.microsoft.com/en-us/windows/deployment/update/windows-update-resources

that last bullet is what finally brings me here to write this. I can follow the instructions up to the point where it's asking me to re-register all the relevant DLL files, but I've found that many of them throw an error when I attempt to register them, and this may be the key symptom that will help identify and solve my problem. For many of the DLLs, I get an error such as this one:

the list of DLLs that the instructions ask me to register that fail with this error are:

• mshtml.dll
• shdocvw.dll
• browseui.dll
• wuaueng.dll
• qmgr.dll

and on top of that, some of the DLLs throw a different error that looks like this:

that list of failures includes:

• msxml.dll
• gpkcsp.dll
• sccbase.dll
• slbcsp.dll
• initpki.dll
• wuaueng1.dll
• wucltui.dll
• wuweb.dll
• qmgrprxy.dll
• wucltux.dll
• muweb.dll
• wuwebv.dll

It's possible that the instructions linked above are critically out of date: it also mentions navigating to a folder at "%ALLUSERSPROFILE%\Application Data\Microsoft\Network\Downloader\qmgr*.dat" to delete some files, but that path is wrong, the correct path is \ProgramData\Microsoft\Network..., and once you get there, I didn't actually have any qmgr*.dat files in that folder, I found file(s) named "qmgr.db" and "qmgr.jfm".

That aside, I'm really hoping all these broken or missing DLLs can help point to the underlying issue I'm having. I've been struggling with this for a while as I mentioned and am open to any ideas, diagnoses, and potential solutions. If you read this in full thanks, and thanks in advance for your advice.