ANSWER: Inconclusive. There are many 3D games that were released, there is no solid evidence, to my research, of the very first 3D character. Wolfenstien 3D and Doom are amongst games mentioned.

Games are often orientated around the type genre. Take GTA 5, you have 3 male protagonists, 2 white and 1 black. GTA is about criminals and the vast majority of criminals are male. In this argument, it would be fair to say theres no reason to add a female characters into this type of genre just for the sake of it.

https://www.theguardian.com/technology/2014/mar/11/video-games-too-white-too-male-women-ethnic-diversity

Mainstream games are becoming more gender bias. Take The Last of Us, both protagonists are both male and female. Then later DLC was released, it was 2 female protagonists, with the new game 'The Last of Us 2' having 2 female bisexual protangonists. The genre is a apocolyptic fictional world.

Women hailed the 2013 boobs of Lara Croft, because they were finally reasonable, for god’s sake — in part because, by then, about half of all gamers were women.

https://melmagazine.com/en-us/story/the-new-lara-croft-movie-and-where-were-at-with-big-boobs

Aside from 1981’s Ms. Pac-Man and a twist ending of Nintendo’s 1986 game Metroid that revealed the lead character to have been a woman all along, major game franchises basically didn’t have playable female characters as their leads at that point in the medium’s history.

https://www.google.com/search?rlz=1C1AWFC_enGB807GB807&q=first+3d+models+game&sa=X&ved=2ahUKEwiri_Ty_63nAhWHWxUIHU3hCc0Q7xYoAHoECA0QJg&biw=1920&bih=969

Seeing a black person in a game is still a strange experience more often than not. For the longest time, black characters seemed to fall precisely into two categories, scary and...funky. Both of these stereotypes are still very much alive, and yet I can also finally see some breakthroughs - games in which black people don't fill a role, and instead get to be just people.

Your average scary black character is at first glance like so many other men in games. He's buff, and he has a gun. What you need to take into account however, is how this stereotype has affected black men in real life: many people still readily draw the conclusion that a black man who looks a certain way is likely to have a history that includes a council house upbringing and a brush or two with the law.

https://www.eurogamer.net/articles/2018-10-03-the-state-of-blackness-in-games

Generally, a greater diversity of characters and stories points to a greater diversity in the industry and of course the people who play games. Games aren't only growing as an industry, they're expanding in their portrayal of the world, and characters of different cultures are an important part of that.

https://www.eurogamer.net/articles/2018-10-03-the-state-of-blackness-in-games

After lots of searching, I have found no real evidence of the first 3D character for a video game. Wolfenstien 3D and Doom were hailed as the first ever 3D games, but in fact they are classed as 'false 3D'

https://www.vice.com/en_us/article/4xaagg/doom-wasnt-3d

Faking 3D
It isn't too hard to fake 3D, depending on what effect you're trying to achieve. It's really just about focusing on what you want to imitate, then isolating what makes something look like that, whether it's depth, or shading, or movement, and recreating that with the tools you're familiar with.

https://www.provideocoalition.com/faking-3d-in-after-effects/

With technology advancing so much and the release of the PS1, 3D games came thick and fast with the releases of game such as Ridge Racer and Die Hard Trilogy amongst many others, I have come to the conclusion that there was just too many 3D games released around the same time, to truely define the first ever 3D modelled character.

Self written

Polycount
The Kratos model for the new God of War was created from scratch with the intent of pushing the technology of what we have done before at Santa Monica Studio

PS2 Kratos 1,200 polygons
PS3 Kratos 5,700 polygon
PS5 Kratos a staggering 32,000 polygons

https://blog.us.playstation.com/2019/12/16/the-polygonal-evolution-of-5-iconic-playstation-characters/

3D Evolution
A. Sutherland invented and developed the first 3D modeling software. Sketchpad was the first program for three-dimensional modeling of simple objects such as cubes or prisms available for the personal computer. Although a computer was too expensive and unavailable to the common man during the '70s, the first 3D modeling software arrived and started a revolution among artists and architects.

https://www.easyrender.com/3d-visualization/a-brief-history-of-3d-visualizations-the-ins-and-outs

3DS MAX HISTORY 3D Studio was released to the public in October 1990. The 3D arena at the time was populated by a diverse range of software running on various platforms: LightWave 3D, Sculpt-Animate 4D, Imagine, Topas, Electric Image, Softimage|3D, Wavefront Advanced Visualizer and Alias PowerAnimator, among others. Back then, the words PC and multimedia were not used in the same sentence, and few people would’ve dared to place their graphics software bets on PCs. The first version of 3D Studio was created by four developers, and its low cost, versatile functionality, and expandability via a plugin architecture would make it the most widely used 3D software in the world.
https://cgpress.org/archives/cgarticles/the_history_of_3d_studio

Social media
has become a powerful vehicle in bringing equal rightss issues to the attention of a wider public, galvanising action on the cities around the world, and encouraging policy makers to step up commitments to gender equality.

https://www.oecd.org/dev/development-gender/DEV_socialmedia-issuespaper-March2015.pdf

Evolution Of Video Game Polygons
A polygon is a triangular shaped flat surface, used in 3D graphics technology to build three dimensional figure. Polygons are connected to one another, creatively positioned, and together make up a 3D image. As a general rule of thumb, the more polygons that can be used, the better quality the 3D image will be.

https://popculthq.com/2018/02/26/evolution-polygons-3d-video-game-graphics/

https://itstillworks.com/12314899/history-of-the-first-3d-video-games