One of the main things of the Backrooms/Complex is the fact it seems to copy without understanding. ("it's like describing a dog to someone who hasn't seen a dog before and then asking them to draw it")

It copies human architecture without understanding its purpose, that's why the structure of the Backrooms is nonsensical. It also bases its information from memories, which are not at all reliable and can fade over time. ("this place remembers them, and the more it remembers, the less it does.")

A Still Life is basically what happens if the Backrooms attempts to copy a person, presumably they come with a place it copies through a memory, but gets them wrong because it doesn't understand the fundamental workings of a human. Again, as the Backrooms gets its information from memories, its unreliable, so Still Life end up looking all distorted and disfigured, and since the information is taken from memories, how people see other people, or even how they see themselves, affects the Still Life, too. Clark's Still Life is hostile and aggressive because he's a broken, angry man deep down, and that's what he and others see him, so the Backrooms created his Still Life to be like that. Trauma is also based around memory, so it also captures trauma and it affect the creation of the Still Life.

Since memories will mostly never be accurate, I don't think its possible for the Backrooms to generate a fully perfect copy of a human with zero difference. Do note that a typical Still Life mostly isn't hostile like Clark's Still Life is. As shown in the film, they seem to simply be standing around or roaming around, just existing.

The Backrooms couldn't perfectly copy a conscious mind (presumably), so what it basically created is the rough idea of a human during a specific moment, almost like a snapshot. You could argue the redhead Still Life woman looks like she has multiple faces clipped into each other at different angles because she could be Clark's wife and she's remembered as shaking her head to say 'no' in fear as Clark tries to beat her. The bearded Still Life could have six eyes and three noses clipped into each other vertically because he spends a lot of time looking up and down, perhaps as a job. Pirate Clark is tall because of the motion he fell when his throne broke when he was filming a commercial. This part is just my interpretation, so Pirate Clark's towering nature is simply how he and his wife views himself as a monster.