The trajectory of history suggests that it’s easier to trade than to steal and easier to ally than to fight.
They absolutely do. From simple concepts like resource competition in which trees deplete the ground or outcompete each other for sunlight (e.g. any forest floor is usually not covered in grass) to parasitism and strangulating vines and whatnot, these guys are hostile and deadly to one another. They just don't run around much.
> through different eras, men have traveled long distances to kill, subjugate, enslave other people
I know lichens are considered "symbiotic" but I'm not sure what you would call a fungus that breeds algae cells and consumes them for nourishment. In that vein we're also symbiotic with pigs, which I find an inappropriate term.
Either way, my point is: Animals aren't remotely as unique as many people think.
Through different eras, men have traveled long distances to kill, subjugate, enslave other people, and to consume everything that can be consumed, we won't change if we start going to the outer space. Being the most advanced species on earth doesn't make us different, as spiders, fish, birds, wolves, anything that moves is determined to kill or be killed, so it's not only a human trait.
Is it a dark forest? We don't know, it may just be an open battleground where intelligence is the final conqueror and that's exactly what rides on top of the arrow of evolution.