I mean, at least one pretty important person died.

No, because they use time travel which is basically a cheap way to bring anyone back whenever they are ready too.

Time travel only worked to bring Saint 14 back for very specific reasons. You can’t just use the sundial to bring anyone back.

You're missing the point. It's the fact that they can make up whatever they want in a fantasy world, and if they just keep finding ways to bring anyone who dies back it starts to make the world pointless. So whether it's specifically time travel or specifically the Sundial doesn't matter, the point is they need to let things stay dead in order to give living in the world meaning.

Okay, yes, IF they keep finding ways to bring people back, sure, but they haven’t, there’s nothing to indicate that they will, and your post made it seem like they have already.

I'm a little late to all of the discussions but Bungie has already done this, and there's a whole expansion dedicated to it. People that have died and came back. Saint-14 Mara Sov Uldren Sov Toland (technically) Crota Sepiks-Prime Omnigul Skolas Phogoth (twice) Ghaul The Gatelord from D1 Oryx's Shadow Fikrul (which doesn't even make sense that he would be a nightmare, given that he comes back to life every week) Riven Dul Incaru In such a vast world like Destiny, where the lore is so in depth. To continually fight the same enemies or have characters die, only to be revived for plot is just weak. What's stopping me from using the Obelisk on the Shore and tracking Cayde's light through The Ace of Spades and joining him in his fight against the Scorn. As much as I love Saint-14, he should have stayed dead because it doesn't make sense in the slightest that we udo a bootstrap paradox just from keying on in his light a few times, vs the 1000's of times Osiris looked for him.

Listing a bunch of characters who technically survived after death is meaningless, when two of the main factions have the power of self resurrection. Also none of the Nightmares came back to life, they’re just illusions. Mara never died, and Oryx’s shadow is just a bunch of Taken goo in the shape of Oyrx, it isn’t a character coming back. There’s a bunch of explanations on why we can’t bring Cayde back, like, tons. It’s really not that hard to find.

Mara Sov did die. But she used the means of Ascension like the Hive to return. During the Battle of Saturn, Mara died along with the majority of her fleet. Uldren was revived by a ghost. Toland physically died The nightmares, while they're illusion to some others. The ones we faces were physical. And the topic was characters dying and returning. So any likeness counts as a return. Which is still limiting this vast world. Omigul died. They retconned her in RoI to "keep coming back" along with other D1Y1 bosses because the 3rd expansions are when Bungie runs out of ideas and decides to resurrect old enemies. As so proven with both RoI and Shadowkeep. Under a very similar process. "Angry enemy faction down on their luck turns to an old power to resurrect old enemies." Fikrul, Dul, and Riven at least have reasons as to why the come back. Also, I would like to see those reasons Cayde can't come back. I've got some time to read, if you have some links or lore tabs that says why he can't. I main a Warlock. One of my canon and in-game abilities is a healing rift. Why couldn't I just throw one down to heal him. At times, the Destiny lore starts to contradict what happens in game. Our Ghost says he couldn't heal him because Ghosts only have one Guardian. What about Shin Malphur, who's Ghost isn't his? But it heals him, and empowers him. Why is Eris still Ghostless if Shin can have a Ghost of his own? Why couldn't Cayde receive a new Ghost after Sundance had her very heavily plot driven death? Why resurrect Uldren. The man who chose the Darkness over the Light?

There is no evidence of Shin’s Ghost healing or resurrecting him. His connection to the Light is presumed to be because he was resurrected by a Ghost as a baby. Each Guardian can only be resurrected once as far as we know, once a Guardian dies after their Ghost has been destroyed they’re gone for good.

Considering that Shin, while having a connection to the light, had no way of channelling it, until after he has Jaren's Ghost and trains. It's safe to say that his Ghost heals him. I can't really imagine a Guardian not dying or having serious injuries while travelling. Plus, he's had the light with him ever since he was a baby. And it's not like he died and was revived by a ghost. Not to mention, after the Red War, Shin is still connected to the light in someway. Jaren's ghost has to be able to heal him in someway. This one isn't backed by much. But I think Jaren put some of his light into his Weapon. Kind of like how Saint-14's Bastion had some of his light in it. And maybe that helps connect Shin and his Ghost. Just a thought.

Guardians have a direct connection to the Traveler that lets them use their abilities, so ghostless Guardians can still use light, they just can’t be healed or resurrected.

Is Shin just a special case for that rule? Because he doesn't know how or can't use his powers until Jaren's Ghost returned to him, but newly risen can and do. And his story never explains how he has light in him. All Guardians, Warlords and Risen were all dead before the Ghosts revived them. How is it that Shin was embedded with light without ever dying?

He did die, as a child.

I know you're talking about the Lost Ghost lore tabs. And while everything seems to line up, Guardians don't age. Or at least they age very, very slowly. Take Saladin for example. His cutscene with him battling SIVA was a little after the Battle of Six Fronts. That's years and years before the City was what it was before our Guardian was revived. Or Zavala's cinematic that shows his life from his first resurrection. He doesn't age. Shin physically ages normally from a baby to an adult.

His aging could be accelerated because he didn’t have an active Ghost, or Guardian aging doesn’t start to slow until someone is in adulthood.