Follow-up...
Downloading KB5008212 and attempting to install it manually after doing a clean boot didn't work. This time I actually see on the update history list that the installation failed, and it shows Error 0x800f0845. So, at this point I'll keep pausing updates till I find a solution to this problem.
Problem solved!!!
Even after trying just about every procedure I found on various Internet resources, the installation of KB5008212 failed by giving me the little white circles endlessly spinning in a circle immediately following the Windows 10 logo after the restart, which forced me to manually shut down the computer every time.
Here is what I finally did, which solved the problem. My x86-based computer's Operating System was Windows 10, version 21H1, and has not yet received a notification from Microsoft that the Windows 10, version 21H2 was available. So I decided to access Microsoft's Download Windows 10 page (https://www.microsoft.com/en-us/software-download/windows10) and manually install the Windows 10 November 2021 Update by downloading the Update Assistant with clicking "Update now", which downloaded the file Windows10Upgrade9252.exe. After the download completed, I ran (as Administrator) the file and let it do its thing. Once the process started, it took several hours to complete successfully, i.e., it installed this new feature package, 21H2, on my computer. While this process was executing, it allowed you to minimize its window, and that allowed me to continue to use the computer.
This morning I checked to see what all was installed beside the 21H2, and, lo and behold, KB5008212 appeared when I checked installed updates. I then undid the "Pause updates" to resume receiving Windows updates, and shortly thereafter three new updates for Windows 10, version 21H2 popped up, downloaded, and installed. One of them, a cumulative preview update for .NET framework 3.5 and 4.8, required a restart. After the restart the computer booted properly, and it's running just fine.
I hope this information will be helpful to some of you who are having the problems with KB5008212.