3 ideas
The station is designed to sustain its crew on its own rather than depend on supplies from Earth. Greenhouses use unfiltered sunlight to grow plants, which provide food and regenerate oxygen, and sunlight also supplies the station's energy. The habitat is treated as a managed biological cycle, not a sealed can of stored supplies.
Without gravity, trivial actions become engineering problems. Walking, drinking, eating, sleeping and keeping objects in place all need new techniques and devices, such as small jet propulsion for moving around. Showing a clumsy newcomer learning these skills presents space habitation as a question of redesigning ordinary routines, not just building rockets.
Once a permanent station exists in orbit, it can serve as a base for launching deeper missions, such as expeditions to the Moon. Starting from orbit avoids having to climb out of Earth's gravity on every trip. Space expansion therefore proceeds in stages, with orbital infrastructure as the necessary first step before interplanetary travel.