Does the airport bus still go to the (largely closed) Abdali station...?
If it does not you can ask the driver to drop you at the 7th circle and take a taxi from there. Make this request clear as you board the bus because your luggage will then go into a separate compartment in the belly of the bus. At the 7th circle your chances of finding a taxi that is willing to use the meter are better than at the bus station. Other than thieving taxi crook bastards, Amman is totally safe, even at night.
When you arrive at 8.30 you can get the airport bus at 10. It does not run more frequently than once per hour, contrary to what the schedule sign says. Also, despite prominent signs the bus does not call at both airport terminals. It only leaves from terminal 2. Departure can be up to 15 minutes late since the driver tends to wait for his "friends" (airport staff) even if they are late. Apart from the fact that the organization of the airport bus service is an absolute disgrace (I assume Royal Jordanian, which strives to be a world-class airline, has no say over these ground support operations) it is highly recommended, being 10 times cheaper than the taxi (JD 1.400 plus JD 0.250 for each bag that goes into the hold).
Other than the bus station, the best place to catch the airport bus for the trip back to the airport is Royal Jordanian's city terminal near the 7th circle. For some bizarre reason going in that direction is a bit more expensive (JD 2), and the bus from there does leave twice an hour. Sometimes... Last departure 10 p.m.