Here are 10 different types of humans.
1. Rival adventuring party, all level 1d6. Fighter has a falcon and an eyepatch. Wizard carries a glass tank of frogs on his back. Thief sneak attacks with his magic glove whenever possible (which rots targets for 2d6 damage whenever possible, cursed so cannot be removed). Fighter2 has a ridiculously high AC and will try to assist his teammates. Fighter3 has a tentacle arm, monstrous strength, and barely any face left.
2. Pilgrims. Armed with glaives, armored in clay armor (as chainmail, but breaks as soon as it prevents an attack) and paper sheets of holy books. They're on a pilgrimage to some shitty room in this dungeon, and will fight to the death anything that they see, because religion.
3. Parasite Incubators. They know what is gestating inside them, and they are ashamed of it. They have come here to die. They will try to warn the PCs away, but they are not fully in control of their bodies. They will attack in jerky motions (-2 to hit), but after they fail their morale check, the do not run away, but instead attack with +2 to hit and move and double speed. One round after being killed, they spawn 1 HD parasites apiece, each of which prefers to grapple faces.
4. Berserkers. Can only be appeased with blood and skulls. Will accept others, but will also settle for the PCs. They're here on a death quest--they will fight Weakness and Evil untili they are killed.
5. Inventors. Here to try out their new inventions. Each carries one invention: d4: fireball crossbow, lightning bolt in a pipe, mechanical wings of fly, trumpet of telekinesis cone. Each time an invention is used, it has a 25% chance of exploding.
6. Madmen. Possessed by ghosts. Will attack PCs with screams, curses, blasphemies, and thrown objects. As soon as one is damaged, they go into poltergeist mode, using telekinesis and magic jar.
7. Wizards. They're here to defend their thesis. Being the prudent sort, they'll attack on sight, amid cries of "Oh dear!" and "Heavens to Purgatory!" They've dealt with monsters and adventurers before, and so they know that the best solution is to quickly kill them out of hand. Beyond that, though, they're not unreasonable.
8. Mutants. They will try to hide their mutations. They will yell at the PCs to throw down their food and leave. They are semi-reaonable, but under no circumstances will they let the PCs past them.
9. Monster Trainers. They are here to capture a specific monster (roll on the rest of your random encounter table). 50% chance that they have captured one and are eager to try it out on the first bunch of PCs they encounter. At least one member of their party will have someone who can do mind-control magic.
10. Paladins. The Warhammer kind. They're here to save innocents and kill witches. Anyone who casts spells or looks weird is immediately punishable by death. And their companions are suspect, at best.
11. Curse Hunters. They are looking for a particular curse, rumored to be in this dungeon, which will cancel out another curse that they already suffer from. (For example, a curse to die in a fire is canceled out by a curse to never be warmed again.) They will provoke spellcasters along these lines. 1d6 of them have death curses, to be inflicted on whoever kills them. They will probably be vocal about this fact. Even the ones who don't have death cure will claim that they do.
12. Abductors. They look like humans, but they aren't. They have fly active at all times, although they won't use this ability unless threatened. If they can surround a person in an airtight ball (requires at least 4 of them) like bees killing Japanese hornets, they will whisk that person away to the other place. The abducted PC will return in 1d6 days, with a new mutation and a transmitter embedded behind their ear. The abductors will take the shape of villagers with broad, genuine smiles.