Celebrimbor, incidentally, is a major character in the Shadow of Mordor video games, though they do some weird things with him that the Professor would probably not have approved of. Who knows if we'll actually see the duping of Celebrimbor and the creation of the rings in this series … technically these events are in the Second Age, but they come awfully close (overlapping, actually) to what we see in Jackson's films. He would sometimes take the beautiful (yet evil) shape of Annatar, who charmed the studded pants off of everyone who met him.
He had a body, and he could change its appearance. Sauron often used a different form which he used to cuckold people and bring discord - this was well before he was only able to manifest himself as a giant flaming eye. Nine mortal men doomed to die greedily took the nine rings offered, and their corruption (and transformation into the Ringwraiths) happened soon after. The three, the seven, and the nine were given out during this time, and as we know, Sauron took what he learned from Celebrimbor and secretly created the One Ring to Rule Them All in the fires of Mount Doom. Another huge occurrence in this period features Sauron making friends with an elf named Celebrimbor, the one who created the Rings of Power. It is in this time that he secures his own kingdom in Mordor and builds his tower of Barad-dûr for the first time. He becomes a major player in the Second Age, screwing around with men, elves, and pretty much everyone else. This period also features the rise of Sauron, lieutenant of Morgoth, and hereafter the major Big Bad of Middle-earth. It would be odd to see anyone else in those roles.
Galadriel and Celeborn also officially relocate their home to Lothlorien in this period, and it should be noted that if either they or Elrond are featured, it is devoutly wished that they continue to be played by Cate Blanchett, Marton Csokas, and Hugo Weaving. Many interesting events take place in these 3400+ years, including (but not limited to) the Noldorin elves securing a kingdom under Gil-galad (who is briefly seen in that prologue), the founding of the Grey Havens, Elrond settling Rivendell, and the dwarves coming together (mostly) in the kingdom of Moria. The Second Age of Middle-earth spans the time from Morgoth's final defeat up through the Battle of the Last Alliance, seen in the prologue of The Lord of the Rings: The Fellowship of the Ring, the first of the Tolkien films from Peter Jackson. Welcome to the Second Age: - The Lord of the Rings on Prime March 7, 2019