Correct. Ainz is not a morally good protagonist. He's a Lawfully Evil Villain who prioritizes Nazarick over anything else in the world, including honor morality and ethics. He has moments that makes you think he's a neutral protagonist who rewards good with good and evil with evil, but every time he has helped someone outside from Nazarick it's because:
1.He had something to gain, nothing to lose and his moral code tells him not to exploit his workers, as he came from a different timeline where Japan became a corporativist hell ruled by black companies who overworked their staff to death, wich happened to his mom.
2.He wanted to throw the few good NPC that live in Nazarick a bone by not hurting their consciences even further.
He's apathetic towards human suffering and his moral code and ethics are secundary to the well being and happiness of Nazarick denizens. he'd gladly let his Guardians slaughter a village full of children if it would make them cheer up were and there was nothing to gain for the future of his country. by letting them live. (this could be wrong and there could be a limit to his apathy, tho. I'd say if he sees Demiurge's happy farm and doesn't scold him, or at least care a little then it's safe to assume he has 0 empathy towards non Nazarick denizens.)
What makes people like him is that he's extremely competent, 90% of the time he goes ham on a kingdom that kingdom was full of people who were incompetent, evil and irredemable.
His moral codes are actually pretty good when it comes to people allied, tied or belonging to Nazarick, with him valuing the opinion of minorities under his government (the few good NPC's), being able to recognize his enemies merits and motivations even if he's not swayed by them, Ainz himself not being that evil when compared to say, Demiurge, Albedo and Shalltear, and the fact he treats any subordinate or people who swears allegiance to him and Nazarick fairly and with respect.
But i admit it's ****** when you stop and think about the fates of some people he wiped out, like, imagine living under an authoritarian government who exploits you and gives you barely any hope for a better future and better social standing, all while mocking you and taking selfish choices that benefit an oligarchy that looks down on all people, and then one day these same people who torment you enrage a skeleton man with their stupidity and now you are drafted to the battlefield to die an unnegotiable horrible painful death along with your entire family for something you not only had nothing to do with,, but are also a victim to. Yeah, Overlord world is a pretty horrible place to exist.