In defense of gmeh1, the OP was asking about MCO not Jacksonville. Each airport is unique when it comes to operating hours. Some airports like MCO are pretty much a 24/7 operation because they are busier and have flights arriving and departing at all times of the day and night. Places like Jacksonville aren't nearly as busy and don't have the same kind of round the clock schedule that MCO has.
Your experience at Jacksonville isn't really relevant to the OP's question because they are two very different airports. What happens at one in no way reflects what happens at the other. It is nice that you were trying to share your experience but in this case it isn't helpful to the OP and her question (but it might be for someone travelling to JAX)
I travel all the time and I know when I am arriving on a late flight at a smaller airport that I better check times for the rental car companies because they may not be open and I have to find an alternative. Major airports almost always have rental car companies (at least the major ones) that are open 24/7/365.
Thank you!!!