Oh true the void has to be pushed back for there to be an interesting story, but humans are in so many other stories that it seems overdone for them to be in here too.
I also just mean the void itself seems kind of overdone, at least as far as things that need to be pushed back.
NINJA'D:
But I don't think that form of opposition is interesting. It's not a nuanced force with interesting ramifications, it's literally just "this thing is in the way of other things existing, and will probably continue to try to ruin everything once it's been created. Deal with it before building anything."
I think a decent analogy might be digging out stone to make your base, and then worrying about caveins. It's not an interesting challenge or nemesis or anything. It's an ambient obstacle at best and a frustrating obstacle to actually doing anything at worst.
If you want opposition, you should try to push an interesting thing into a different interesting direction, not just declare yourself an obstacle to all interesting things and hope to be interesting by definition as a result.
Also, I don't know that they'd be my first choice, but I do like humans when they're defined as sort of action move hero-esque. And a few other ways (navally/coastally inclined is interesting), but usually not "they're flexible" or similar.
Ninja'd.