You may well have noticed there are only four moving civilians available as stock models, and three look identical. That seems a little sparse to populate an entire planet, especially since they're all male.
Therefore this is a library of animated human models to put in your creations.
There are just under 300 models in total in here which are based on about 65 different model meshes with variations in colour and action. You should be able to populate a largeish airport without too much saminess.
These will show up under 'ahq' in the SDK object list followed by a short description of the model and action.
Most are simply standing or sitting with a short loop of movement or action such as talking, waving, stretching.
The sim quickly reduces frame rate as you get further away making the action jerky with more complex animations such as walking so there aren't very many of those.
These are all stock animations created by Mixamo, an online animation site, so they're limited in number and variety.
If a model comes in a version with a different colour it will have 'C1' or 'C2' etc after the name so you can use it in the same scene as the original and not be too obvious.
In the SDK object list search -
'guy' for a male.
'gal' for a female.
'boy' for a... boy.
'girl' for one of those. There aren't many kids. I can't stand them.
'business' for some smart people.
'beach' for some gorgeous flesh.
'Fireman', 'airline' and 'security' will turn up some airport firemen, security guards and airline pilots. 'Old' will find some hot elderly people if that's your kink.
The most common actions to search for are - 'sit' or 'stand' obviously plus 'idle' 'talk' 'walk' 'phone' and 'wave' with a few others sprinkled in.
Some of the models are very good. Some are awful. Some are downright disturbing. I didn't make any of them. I scooped them up from various sources.
There are way, way too many white people, but since 90% of human 3d models seem to be Japanese schoolgirls I did my best.
Most but not all models have LODs, but obviously the animation is the main strain on computers. Interestingly when you hit a certain number of visible moving models all of the animations stop in unison at once. I can't be bothered to count that number but it's a bit over 200 animated models.
You'll probably get bored of looking at these rapidly but it's obviously an infinite subject. I'd call this more of a start than a final product as there's lots to refine and more and better organised categories are definitely required.
The second download is a collection of thumbnail photos of each model.
Model credits - blendtek, thunder, mohsenmousavi2313, Udara Sampath, mike alger, rusty greinder, tural 3d