One of the aspects of NuBSG's retconned backstory that never made much sense to me involved the Final Five making the Significant Seven. So they show up, bring some kind of spiritual salve to the Colonial-created Cylons, and then convince those Cylons to turn most of their race into slaves (the Centurions / non-humanoid AIs) and make themselves mostly a bunch of clones of only 7 different faces / personalities. It was all probably just a buncha crap made up on the spur of the moment to justify what how the Final Five fit into everything.
But it still would have been nice to see it play out first hand, and perhaps come up with a better way of presenting it and telling the story.
I always assumed that it was Cavil who basically changed things around so that the Centurions were made subservient. It gels well with his personality, motives and the scenes we see in "Six of One" and thereafter. While he may have wanted to be the "best machine he can be", this idea was an obvious contradiction of the Centurions motives, seeing as how they allowed the Five to construct humanoid versions in the first place.
It would seem the overall intention of the Centurions and the Five was to do a "do over" of the Earth humanoids and maybe somehow make a lasting peace with actual humans, to later include hybrids like Hera who would become "the future of both races" and "the shape of things to come" (which kinda sorta happened anyway).
This is in stark contrast to Cavil's view of things and, particularly if he had help from other vexed Centurions (the old school models), it's not outside the realm of possibility that he could've managed all of it on his own. He was strongly motivated, which "No Exit" makes clear.
Evidence from that episode seems to suggest that he was not only the first complete version of the new humanoids, but also someone who worked directly with the Five. This suggests that his role was more that of a liaison or partner than a mere prototype. So basically he was trusted by the Five and the Centurions and he betrayed that trust. This left him no choice but to block the memories of his siblings lest they turn on him before execution of the Plan.
As for the seven, it has been speculated before that it was not the intent of the Five that there only be seven, but rather that Cavil's betrayal went into effect before they could finish their work, perhaps create more models and make it so that they could procreate biologically. Having boxed them, Cavil alone lacks the knowledge and, rather importantly, the motive to finish the job.
It seems to be that, from a broader perspective, Cylon history can basically be divided into "Before the Five" and "After the Five", because their existence seems to wildly diverge between them. It of course remains unclear what role, if any, the events of "Caprica" played in this. That and the origin/purpose of the Guardians will probably only be semi-resolved in comics and other semi-canon works (if ever).