Jupiter is a planet made of gas. Different corporations have settled near this giant to mine valuable gas, the whole environment of Jupiter is affected by these competing corporations. There are ships mining the gas directly on Jupiter's surface, other vessels that transport gas to the next station, where it is refined to produce fuel.
For design inspiration think about the industrial area in your city. There are no buildings on Jupiter of course, but like in industrial areas in your city, everything is designed to have a certain functionality. Aesthetics are not important, only functionality. That also means that machines are dirty, logos are scratched and paint is flaky.
Sure there may be a bar or a club or something which is designed nicely. People can relax there after all long and hard day of work. However these places are not expensive or clean, but a less hostile environment than the rest of the Jupiter orbit.
When designing content related to the human race in Orxonox, the most important thing to keep in mind is really simple: keep it human. In terms of technology, Humans are not as advanced as the average alien race. That's why they still live in the same solar system, they lived a thousand years ago. In fact, Human technology in Orxonox resembles todays technology strongly, both in function and design.
Spaceships and -stations
Human ships and stations are large heaps of metal that consume lots of fuel and fly relatively slow. Metal is the only material that proved to be cost-effective, hard and durable enough to withstand the strain by attacks and collisions with the occasional asteroid.
The ships look similar to todays modern aircrafts, although their shape is a little less aerodynamic, because they travel in space and not inside an atmosphere. Most of the human ships are symmetric, which simplifies the modeling process.
Space stations are mainly constructed from a set of generic modules, which makes them look a little bit chaotic. They are built in every size. Some small stations are unmanned and serve only as a gas station for traveling vessels while other stations are complete cities in space where thousands of people live and work. The larger stations are not equipped with their own engine. If they want to move, a bunch of towships are attached to them to pull them through space.
When modeling, you can add various details to your ships and stations, that are typically human. These include ordinary thrusters, a cockpit, some kind of extensions on the side, where weapons and auxiliary gas tanks can be attached, survival systems for the human crew, doors and hatches in the hull, ducts, cables, service panels, a cargo bay, lights, antennas, devices for docking onto other spaceships or space stations.
Texturing human ships and stations is a straight-forward process, but it can be time consuming. In order to make your model look interesting you will need many different patters and materials. For the hull you can keep to some patchy metal surface, but it doesn't need to be metal gray. Feel free to add some color, as long as it looks nice, fits in and can be used together with the existing Human entities. You can get a lot of inspiration from looking at airplanes, ships, industrial plants, rusty surfaces, metal girders and fences, cars, trains and other machinery.