Ever notice how many times Celebrimbor echoes some of Tolkien's own villains? He wants to use the Enemy's own power against him, like Boromir. He tells you that you need an army of orcs to fight in Mordor, like Saruman. And how do you get said army? You enslave them, you bend them to your will, much like Sauron himself bends his ringwraiths and other servants to his will. Celebrimbor calls himself the Silver Hand, much like Saruman is the White Hand.
Even the branding of the uruks is similar. Remember how Galadriel says that yeah, she could use the Ring to defeat Sauron, but that that would be a bad idea because in doing so she would simply be replacing one tyrant with another? Well Celebrimbor clearly had a different opinion on that, since that's exactly what he tried to do. He even echoes her "all shall love me and despair" with his own "all shall fear me and rejoice". This game's Celebrimbor is basically a mash-up of Tolkien's own villains.
In terms of his importance to the story, Talion is little more than a vessel for the elf wraith. Firstly, Celebrimbor feeds him lies throughout the whole game. This whole "amnesiac elf wraith" schtick? Yeah, it's bullshit. We're told late in the game that Talion is cursed because Celebrimbor chose him as his vessel and could leave him at any time if he wanted. Moreover, Celebrimbor uses his "Nan iChir Gelair" line when interrogating uruks right from the start, and as you learn towards the end of the game that line means "I am the Bright Lord (of Mordor)", a title he adopted when he claimed The One Ring and led an army of orcs of his own against Sauron and his forces. He knows perfectly well who he is and what he's doing right from square one. He might even be mind-controlling Talion to an extent. We know that being mind-controlled by Celebrimbor turns the uruks' eyes light blue, right?
Well guess what.