NWN (and likely DnD's) racial types are pretty granular in some ways, and super vague in other senses.
You'll never make sense of it, aside from undead or oozes. (And I bet a lot of people think bone golems are undead when they're actually constructs *wink*)
The best bet is to look at the NWN wiki and see what they categorized as whatever, and extrapolate from there with POTM's specific things.
Undead are undead, various forms of dead animated by negative energy. Zombies, skeletons, vampires, etc.
Constructs are things animated by magic but are otherwise inert. Golems.
Oozes are oozes. Slimes, cubes.
Elementals are elementals, beings of elemental forces. Fire elementals, water elementals,
Outsiders are from other planes (including elemental planes). So, Salamanders, pit fiends, balors, cornugons, etc.
Animals are animals. Wolf, rabbit, mink. Normal animals that could be from IRL.
Beasts are a specific category of mythical but NOT magical animals. Stirges, bulettes, and grey renders are these.
Magical Animals are mythical AND magical animals. Winter wolves, krenshar, manticores.
All the player races are their own creature type. Yes, this includes half-X's. I have no idea what a caliban from ravenloft counts as. Half-orc?
Shapechangers are things that turn into something else. Werewolves, wererats, etc.
Abberations are either things from the outer whatevers, like...beyond the planes. Or things that got messed up for some reason. This means aboleths and the various freak-monsters in markovia. And umber hulks.
Dragons are dragons.
Reptillians are lizard folk. That includes kobolds (are our kobolds the same? beats me), sahuagin, and lizard folk.
Goblinoids are goblins. But also hobgoblins. And bugbears. And goblyns, which are goblins.
Giants are big mfs. Giants, ogres, and trolls. And scrags. Except scrags are the result of experimentation, so they might be abberations. Except I don't think they are, I think it's still giant.
Monstrous humanoids are humanoid monsters that aren't part of the other categories. Minotaurs, harpies, stingers...maybe other things people have said in the thread! Maybe not.
Vermin are mostly insects and bugs. Except the spiders that aren't.
Long story short, being a bad person is not what makes someone a monstrous humanoid.
And when you pick your favored enemies, you better pick the right ones! (those obv are elf, half elf, half orc, gnome, and halfling)