Are <5.0 main villain> fanboys also supportive of <6.1-6.5 main villain>? *SPOILERS*

[MikkoAkure]

Both sides are perfectly reasonable stances to hold and the solution to resolving them isn't murder everyone. She allowed Zodiark to happen because she needed him as a shield for her new world and then used his existence as an excuse to get 12 people to give up their lives and more of their souls than they seem to know they will be losing so she can kill everyone they know and love.

But let's say I'm wrong and the lesser life isn't animals. Let's say that it's sentient beings, us even, let's say they wanted to sacrifice cat boys and bunny girls. Well, whatever life they were fighting over was sundered, so RIP. And the people who wanted to protect that life and agreed with her? Also sundered. So attempting to humanize the third sacrifice to dehumanize the Ancients doesn't work because whatever the third sacrifice was she destroyed it in the Sundering. You can't save anyone by ripping them to shreds and mutilating them to the point where they are no longer recognizable and reducing their lifespan by a factor of hundreds. That's not how saving works.

Her goal was not to save the third sacrifice, her goal was to make sure the future was shaped by her hands and hers alone.

This isn't all just Venat's vanity project like you keep trying to insinuate. The movement against Zodiark also seems to have started without her initially as well.

This undertaking, however was not without its opponents. There were those who contended that the volitile failure of creation magicks was a clear sign that mankind could not continue as it always had. Whether the calamity had eroded faith in the Convocation, or the grim glimpse of despair had simply woken people up to a new perspective, the fact remained that the anti-Zodiark sentiment was growing, and had found a champion in a woman by the name of Venat. Her followers were too numerous to ignore, but the Fourteen would not be dissuaded from their plans. A schism formed in the ancients' society, and conflict between the tow factions erupted in earnest.
[...]

The faction lef by Venat feared that the world would not survive a second coming of the Final Days. To prevent this calamity from ever happening again, they arrived at a disconcertingly familiar solution
[...]
Venat convinced her followers that Hydaelyn and Her sundering was the only path forward.

According to the 3rd Encyclopedia, her faction knew about the Sundering and the whole reason they did what they did is because they didn't believe that the world would survive a second coming of the Final Days. The faction was also more than just The Twelve and it was sizable among the surviving population of Ancients.

Another thing to remember is that the people who were killed during the Final Days would not come back and that didn't look like any small number. The original world pre-Final Days was never coming back and if the third act had gone on and those sacrificed did indeed get their bodies and individuality back, then the Ancient world would still be forever altered with a tempered convocation and a literal god of their own creation at the center of their society as the rest of the universe collapsed around them over millennia and Endsinger speeding up the heat death of the universe.