Not a normal human
What's funny to me is that even games back then were making fun of them. There's that Lara Croft parody character in Spyro 3 who complained that she spent the entire day shoving boxes around.They're low-poly count and easy to texture, and they're easy to animate and subject to physics and/or player interaction. At the time, CPU and graphics resources were very limited, so boxes were the go-to element if you wanted things in your environments that players could manipulate to solve puzzles and/or destroy without having to worry about deforming your level meshes or dealing with complex animations.
One of the reviews on GOG noted that the original allowed for up to five different movement speeds in addition to 8 degrees of direction on an analog stick. Meanwhile the PC version only has two speeds and 4 directions.I haven't played the PC port but I can't imagine the game is very good without a controller.
I was expecting it to be something similar to Tomb Raider, which is playable on PC but somewhat uncomfortable with a keyboard, but that right there says that a controller is basically required for Soul Reaver. People have found workarounds, like Xpadder and such, but it doesn't always work apparently.