You're hoping the humans (as the underdogs? DEX covered that one so I won't) get some kind of victory in the future? For what? Kicking a hornet's nest and getting stung?
You're worse than the king who thought they deserve reparations for a failed invasion.
You're obsessed with retribution over justice. As an American, a culture that normalized retribution over rehabilitation, even I find your preferences troubling.
You're so insanely wrong, I almost have to believe you're trolling.
Orcs ravaged the region because Clayman's pawn turned them into the Orc Disaster, tried to control them, got eaten, and Clayman was intending to finish them off. Presumably for the same reasons Rimuru just slaughtered 20k people, sprouting a demon seed.
Humans didn't enter the forest because of the dragon sealed there.
Monsters were always intelligent, they just weren't organized. The dryads are smart. The goblins are weak, not stupid. The ogres (Benimaru, Shuuna, Shion, etc.) had their own culture and village until the orcs swept through. Hakuoro is known across the land as a sword fighter. He's trained people before Rimuru came into play (other characters recognize him). The orcs had their own culture before climate change or whatever drove them to starvation. The lizardfolk had their own tiny kingdom. Milim is a monster. Yuzurania is a nation of monster-hybrids. Etc.