I feel like I understand communist theory pretty well at a basic level, and I believe in it, but I just don't see what part of it requires belief in an objective world of matter. I don't believe in matter and I'm still a communist. And it seems that in the 21st century most people believe in materialism but not communism. What part of "people should have access to the stuff they need to live" requires believing that such stuff is real? After all, there are nonmaterial industries and they still need communism. Workers in the music industry are producing something that nearly everyone can agree only exists in our heads. And they're still exploited by capital, despite musical instruments being relatively cheap these days, because capital owns the system of distribution networks and access to consumers that is the means of profitability for music. Spotify isn't material, it's a computer program. It's information. It's a thoughtform. Yet it's still a means of production that ought to be seized for the liberation of the musician worker. What does materialism have to do with any of this?
There is no evolutionary niche better served by perceiving truth than fitness, except perhaps for the niche that humanity has created for itself by inventing technology that is capable of destroying the Earth's habitability to human life. And a situation like that has never existed on earth before now, so there is no way any organism can have adapted to it.
It's very unclear what you're trying to say because you're using terms with common definitions in evolutionary biology but in ways that make no sense, but also difficult to understand as profound or meaningful if I try to understand them with other definitions.
For example, fitness isn't an evolutionary niche at all. In evolution, niches are relevant to fitness, as they are patterns of (often mutually-excluding) ecological roles played by different organisms over time and space, suggesting some common constraints and situations in the overall fitness landscape. But fitness is not itself a niche. I have no idea what you mean by niche otherwise, but it doesn't make in the context of the field you're wading into.
Anyways I'll try to explain this more by addressing the rest.
This is also not a niche. No other organism, to our knowledge, has such a role or can have it ecologically framed. It's like saying Elon Musk is the best person on the "South African failson that owns SpaceX" team. It's just the one guy, there's no team.
So what? There's no clear point here.
It really feels like you've read some pop science and maybe didn't really understand it. Do you think that's possible?