> How did they make humanoid models in the 90s? Was it done with a character creator? Did they often copy a generic model and alter it?
In the 1990s there wasn't really any single solution to this problem, everyone just came up with their own. It's possible there was some Japanese software I don't know about, but I always just attributed 1990s Japanese dominance in this area to tribal knowledge -- a lot of the same artists working on the same games with similar-looking characters. "Copy a generic model and alter it" is probably closest to the truth here. Making 3D models was a tough business in the 90s, there were no tools like zbrush and artists would almost always be working directly with the poly-optimized in-game model.
In other contexts (like prerendered images or animation), Poser was used a lot back then but it's my understanding it wasn't very popular with professionals. I don't think Poser was used much for games either, if at all.
In that case, you could look at 3D scans of people. If you bring them into a CAD application, you can make point-to-point measurements that would be 3D, which would be more accurate than those taken from photos. There's a pretty old program called Poser https://www.posersoftware.com/ that uses modeled figures that are fairly accurate, but there's increasing availability of scanned data now: 3D Scan Library - a collection of dynamic poses viewable from a full 360 degrees. - Bodies In Motion
Oddly, "playing with dolls" would help. There's a more grown-up version in model and art shops but same idea. Even digital for those with the money.