I have a theory about Destiny 2. It's kinda wild but just hear me out.
So way back in the Season of Dawn, we see our grave. And on top of our grave was a sword. Flash forward to the Final Shape, and we get that sword (Ergo Sum). Initially I thought the timeline we see our grave in was the one where we failed to stop the Witness (or we did and it cost us our lives).
But flash forward to now. I got some dialouge from Bael where he says he sees us dead at his hands, so why does our tomb remain empty? Combine this with the Seer shell lore where XI says because we make our own fate, our tomb will always remain empty.
Add to this: The Shattered Cycle leaks. We were supposed to bind ourselves to III and become the fated Weapon. But we go "nu uh" and bind it to the Traveler instead, which is why the Traveler would start to heal.
So here's my theory: The timeline where we see us in our tomb is the one where we decided to bind III to ourselves and fight the Winnower that way. We have the sword, our tomb gets mentioned a LOT all of a sudden. And who knows what binding would've looked like/what it would've done to us had we gone through it? Also to consider, we are the god slaying killing machine, but the Winnower would be like nothing we ever faced before.