I will however note that part of the reason copyright developed when and where it did is the devlopment of the printing industry, which created the problem of mass-produced copies in the first place; that had of course never been an issue in the day of handwritten manuscripts where it would often take almost as long to copy a book as it did to write it.
Way back when (c. 1986 or 1987), I took some University of Ithra courses. Ithra is the SCA version of "university" in which people can take an amazing variety of classes on various aspects of medieval life from fighting and armoring to cooking, more kinds of sewing and embroidery than I'd ever have guessed existed, and the "chivalry & courtesy" class included how to use various items and layers of your clothing to flirt during dances.
The class relevant to the above post is calligraphy. That's one of the basic Ithra courses that most people take, along with basic heraldry and dancing. Even though we used modern calligraphy tools (no real feathers, thankyouverymuch; I bought new pens, nibs, and ink from a stationery store), producing a correctly-formed word is a challenge at first. Then you're handed a sentence that uses every letter of the alphabet. Then you get to try a short poem. All the while, you're concentrating on keeping the nib at the correct angle so the letters come out right and you use the right amount of ink.
My hands hurt by the end of the session. But the payoff was when Baron Edward Ross (our instructor) came by to inspect my work and said, "This is good, have you thought of becoming a scribe?"
That was high praise. Scribes are in short supply, when you consider that (at least back then; current policies may have changed in the 25 years since I was last active) every time someone is granted an award, they're supposed to get both a promissory scroll and a huge formal one.
I'm not sure whatever happened to my promissory. It's a one-page standard size proclamation that I had been granted an Award of Arms, that means I'm on the lower rung of nobility and can use the title of "Lady". It also entitles me to display my heraldic device on anything from something I own (as a means of identification) to a formal banner to display at court.
A scribe who has practiced regularly can produce a one-page document that isn't that fancy without too much time and fuss. But I never did get my big scroll, simply because by that time the backlog was years long. Those large scrolls are the super-fancy ones with illumination on them (some people just specialize in illumination rather than do the whole thing).
I could have commissioned someone to create it for me, but that cost $$$. If I'd taken Baron Edward Ross up on his suggestion, I could have made a tiny dent in the backlog of scrolls owed to people - tiny, because to do it right took months.
I never did become a scribe in the formal sense, but there were a few occasions when I'd do some calligraphed menus for the feasts.
One other thing I'll note about calligraphy: When you go to the effort to do it well, it has a side effect of helping you to improve your own everyday, mundane handwriting. My handwriting had been ruined in college due to years of hasty note-taking and jotting things down really fast while the instructor was talking. Calligraphy helped get it back under control and readable again.
Generally, if a company hold full copyrights to a work, it is because that work was created as work-for-hire on their behalf by people they hired and directed to create that specific work, not because they purchased the entire copyright of the work.
As in "house names" for various series? What comes immediately to mind are "Carolyn Keene" and "Franklin W. Dixon" (Nancy Drew and Hardy Boys series, respectively), and "Peter Danielson". It was a surprise to learn that there was no real "Peter Danielson" who wrote the Children of the Lion series. It was actually the work of four different authors, though there was one of them who wrote the first dozen or so. It does explain the radical change in focus and style of the last three books of the series.
Far more common, when a work is created by an individual creator not working for hire, is that individual rights that make up the copyright will be negotiated separately. The right of publishing in one language, the right of publishing in another language, the right to make a theatrical adaptation, the right to make a video game adaptation, the right to make a televisual adaptation, the right to make a cinematic adaptation, etc. Moreover, beneath those rights there remain the most fundamental right of the author: the right to create further works derived from the original (ie, sequels, prequels, midquels, companion series, etc), and the right to modify the original (write a modified second edition, etc). Sales of those rights, particularly in the same. So, it will be really rare that an artist retain no right based on their copyright.
Every so often, Robert Silverberg will mention in his email group that one or another of his books will now be available in such-and-such a language. Yes, there are people who are completists who will buy his books in a language they can't even read. Mind you, it's good for the readers of that language to be introduced to Silverberg if they haven't already read his books in English.
The other work that I'm reminded of is The Handmaid's Tale. The same people have the rights to both the 1990 movie and the TV series. This explains why there are some scenes that are so similar, down to identical dialogue (that may not necessarily be in the novel). Most of the people I interact with on TrekBBS or YT regarding this series don't even know there was a movie adaptation in 1990, so they remain unaware of the identical dialogue.