Please don’t call yourself stupid. The common internet slang for that is ELI5 or “explain [it] like I’m 5 [years old]”.

I’ll also try to explain it:

Docker is a way to run a program on your machine, but in a way that the developer of the program can control.
It’s called containerization and the developer can make a package (or container) with an operating system and all the software they need and ship that directly to you.

You then need the software docker (or podman, etc.) to run this container.

Another advantage of containerization is that all changes stay inside the container except for directories you explicitly want to add to the container (called volumes).
This way the software can’t destroy your system and you can’t accidentally destroy the software inside the container.

I think you flll for sarcasm.

Have you been near some sort of news in the last years? Corporations using windows get hacked regularly and they are far off from having everything in a database somewhere. You have no fucking clue. What you are describing is the dream of corporate security newbies, but no big corporation let alone some state government is anywhere close to that.

They have massive shares, where all the people can read and overwrite everything, they open all attachments directly on their machine and click away all warnings without reading them. (Who needs USB if you can mail malware directly?)

This is hell and in Germany dozens of smaller or bigger government networks were hacked and massive amounts of data encrypted last year alone.

Which is good, since M$ Office is still one of (if not the) biggest security holes in all of software due to its macros and how no one uses them securely.

Also also doing things the OS way will lead to less changes in the long run since Microsoft can and will change their layouts as they please, but a well maintained FOSS-fork can stay one way indefinitely.