The precursors to my understanding are god-like beings whom the forerunners managed to rise up against and destroy somehow. They inherited the mantle they claim.
Question, why were the forerunners able to defeat gods? And at that claim a title I think the precursors meant for humanity?
Question 2, also why is it that humanity never stood up for their claim to the mantle earlier during the forerunner-precursor revolution?
We don’t know how the Forerunner defeated them nor do we know what Humans were doing at the time. Humans have no claim to the Mantle anyway as we are only next in line to be tested. Our worthiness has yet to be determined.
The Forerunners likely destroyed the Precursors from the inside. Suprise attack and strategy (They’re only described as god-like because no one knows much about them)
I’ve always associated the defeat of the precursors with the destruction of the Forerunner home-world. Since the nature of the war was covered up and forgotten, I assume the history of a series of accidental novas that wiped out the former core of Forerunner space could be faked as well. It sounds like such a cataclysmic event that it must be related somehow. We also know that the Precursors struck first and the Forerunners retaliated. So if not, their endgame and victory, maybe the surprise attempt by the Precursors to exterminate them?