There's faulty, and there's backstabbing and trying to kill the person who saved your life. Multiple times.
There's flawed, and there's leaving your wife to die for a piece of pussy.
You will admit that there are degrees, and most of the named characters are at the very bottom of the asshole spectrum.
Torago is the only good person, always willing to help others (everyone, not only Maname), even at her own expense.
The elder and the islanders are neutral, they are just ignorant, and by their fault: they are just the products of their society. Could have they been better? Absolutely, but in their place, most of us wouldn't have either.
Then we have the bad ones.
The two guys are reduced in their human status: they are guided by their lower instincts and refute societal agreements in order to satisfy them, without almost no actual concern for others. They lie, steal, betray, and almost killed for a couple of blowjobs: this has ALWAYS been seen as despicable, no matter where, when and in what society, because it undermines society itself.
And finally Maname.
Maname is properly and utterly evil: her actions are deliberate in choice and many times gratuitously cruel. With a hint of enjoyment, even. She doesn't recognize a human dignity to others, she just see them as stepping stones or tools at best, obstacle to be removed at worse. They are not people, just things. She has been put in a difficult situation, but the way she addressed it was her own choice.