In America, everything published before 1923 is in the public domain. Starting in 2019, works published in 1923 fall into public domain, and every year after that the line moves forward. In 2020, 1924 goes into public domain; in 2021, 1925 becomes PD, and so on.
That said, LOTS of things published after 1923 are actually in public domain, because reasons. You have to do your research on everything. George Romero's original abomination NIGHT OF THE LIVING DEAD is in public domain because of a negligent producer. That's why you see cheap DVDs of the godawful thing all over the place, from cheap DVD publishers. That's why it had to be remade. Not that it staunched the flow of disgusting and witless ghoul movies and TV shows.
The law is slightly different in Europe, but RWS is still in public domain by any standard.
The only way US Games or anyone else can lay claim to a copyright on them is by modifying the designs in some way. Then -- if you copy their modified design, you are indeed in violation of the copyright. The same way THEY would be in copyright violation if you took Miss Pamela's original line-art and recolored it, and then they published your colorings without your permission.
But -- why would anyone do that? Miss Pamela did a beautiful job coloring her own drawings. The world doesn't need a recolored PCS or any other kind of PCS knockoff any more than it needs more ghoul movies. It's your responsibility as a creative person to create something new.