X-Plane starts your flight at the end of a runway by default. If you want to start at a ramp or gate, you will need to go into location > Customize and pick that start.
Make sure your "number of world objects" rendering setting is higher than minimum to see buildings. Keep in mind many of X-Plane's default airports have not been improved with buildings and may only have a runway and simple taxiway. KSEA & KATL are good airports to use for all the features of X-Plane 11, including service vehicle traffic.