I think I realised something (spoilers)

The moon presence is the Hunter symbol upside down!

Even during the cutscene it looks like it?

Also during chalice dungeons you sometimes see the same symbol and their hunters are similar looking despite pre existing the hunters of yarnham!

This would mean the great ones are stuck in some kind of enteral war against the moon presence and we are pawns!? Think about it, the Menis ritual must be stop to end the current hunt, and to stop the Menis ritual we have to kill Margo’s wet nurse causing the old one baby/vessel to no longer exist preventing that great one from gaining a physical body in the waking world! This would put the moon presence against great ones who are trying to gain a physical body by being born in the womb of women at the end of a hunt!

By killing the moon presence we are breaking the cycle that is preventing old ones from becoming once again apart of the waking world which would mean they would now bring about a golden age to humanity?