The visitors don't really represent anything specific.They're just based on random memories. The planet/alien doesn't understand humans any better than they understand it.
The planet Solaris is a post-Instrumentality world.All life on the planet is a single being in the form of an ocean of goo. How could one creature have evolved to become intelligent? Obviously, it didn't start with one creature. The "thinking ocean" is the result of an extreme Assimilation Plot.