Were Jesus and Mary both already ascended or enlightened humans who simply returned to pursue a life mission of great importance, and returned to the divine realm in a fashion normal for a fully enlightened human, or were their respective ascensions one time events never before achieved, and never again in need of repetition for those two individuals?

There were other prophets who ascended in like fashion described in the Scriptures. There may be others who undergo a similar visible ascension for similar purposes, to create an event for purposes of inspiration and encouragement, but again those are events that were not singular but not intended to be commonplace nor repeated by the mass of humanity. In actuality it matters little how you ascend—that will be taken care of on your behalf through divine oversight and energies. The pressing question for you is when might ascension happen? There are many times when the future projection of human history has answered that question as "never," meaning that ascension was not in the cards, so to speak, at that point in time. The likelihood of ascension taking place in the first instance is the readiness of humanity which requires you to be out from under oppression and subjugation by the darkness and to have sufficient healing to have completed your mission here in solving the problem of evil as well as its consequences, and the latter are represented by all the woundings to human souls as well as all of Gaia in various ways directly and indirectly. There must be sufficient restoration and healing for readiness to ascend because it is "Earth business" that has happened in the physical plane and must be solved within the physical plane. So this is your incentive to get going and see to this if you want the future to go your way.