My hunch for why Uninvolved can die of old age is that Uninvolved are fueled, or kept living, by the amount that their race sacrificed. Or maybe not sacrificed per se; but rather their lifespan is somehow related to the age and/or proliferation of a race.
Maybe the total years of history of the species before their last generations hits the "Ascend" button plays a part. Maybe only the number alive at the time of ascension matters. Maybe the amount of experience and age of the people alive at the time of Ascension, matters (i.e. If everybody is super-old, that means more power, because there's more experience and weight). Maybe youth matters instead. Maybe population at time of ascension numbers matters the most; maybe the amount of people that died throughout history (hence, short age and quick generations for a species might actually mean more fuel); maybe physical expected lifespan influences Ascended lifespan. Maybe the physical brains and mental make-up of a race matters -- those races who can physically live a really long time without going senile or crazy, can live longer as Ascended, because their "your mind does not fail with age" thing transfers helpfully to a post-Ascended state.
But maybe the reason they can die of old age, is because after a race ascends, there's no more living members of that race left. There's nobody to generate more energy. So they now have a finite lifespan.
That might also be a reason for why the Shiplords harvest the other races, to refill on some of that energy for themselves. Or to deny some of it to the future Ascended version of that race. Whether they use it to keep their semi-Ascended fed, whether they just use it to fuel their anti-Ascended weaponry, whether they fuel some of their most advanced technology, whether they use it to fuel their vigilance against eldritch beings or something, who knows. Or maybe they use it to pay taxes to those eldritch beings! Or maybe they don't vampirize off of other races at all; maybe the tribute is just to instill trauma in the races, and condition them and drive them to Ascend.
Maybe they're just dicks. Maybe they've just been doing the Imperialism thing for so long, that it just because their modus operandi and way of life. Maybe that's all they are. Imperialistic dicks. That's happened in human history; I don't see why it can't happen in galactic history, too. (God knows I would prefer this to be the answer than for the quest to reveal at some point that, no, there totally is some metaphysical reason why somebody might have a reason to commit galactic xenocide and for you to be glad for it! No. I don't want some genocide apologia. Or trying to give 'reasonable' metaphysical reasons for genocide. Cultural and historical and psychological reasons are enough; the metaphysics of a world shouldn't provide any excuses for that, otherwise you've just built a world where you've input into it an excuse for genocide.) (Like, if somebody went on an annihilation spree out of a desire to end all other life so as to prevent anybody else from Ascending? That'd be one thing. That's a horrible, but straightforward and relatable, reason. You're doing something horrific because you've got nukes and you want to prevent anybody else from getting nukes, metaphorically speaking. Hell, just having a weird religion about it? A religion that glorified suffering/sacrifice/death, and which over time just grew into this star empire that would oppress and exterminate other races? That, too, would be fine. Well, not fine fine, but. But having something like a metaphysical reason, some part of the universe itself, being for why somebody would do this and think "I'm doing you a favor!"? No, hell no.)
(In the end, I'd much rather the Shiplords reasons to be political, cultural, economical, or religious. Historical reasons, basically. Cultural forces that simply maneuvered their civilization into one that did this. Maybe ones that grew out of hand. Or that they started doing some of this, and then just eventually even forgot why they were doing this. And in the end, just continue doing it. Not... because there are Cosmic reasons to be doing this. Not for them to "Have A Point." (I can't express how much I would hate for that to turn out to be the case. No. Genocide's genocide. Do not write a setting to excuse, justify or allow for the possibility of 'But there might be a point...' for it. Just go with the usual reasons for why nations would do horrible things.))
I'm wondering now, though. Can Practice create 'armor' or 'shielding' for the Uninvolved? If the Uninvolved are uniquely vulnerable to anti-ethereal weaponry, while humanity can resist partially due to still being material, then can humanity do something about that? Maybe a joint effort of Practice and Uninvolved can result in something as resilient as a human Practitioner.
Other things I'm wondering about, is if Practice can create a structure or place that would be hidden from the Shiplord anti-Uninvolved scanners. Thereby providing the Uninvolved a way to actually visit the world, without tripping those sensors.
Or, if human Practitioners can... I dunno. 'Channel' Uninvolved in some way. Hell if I know.
Also also: can Humanity -- and the other alien races, too -- use the Second Secret to start recreating the old racial bodies of the Uninvolved? I mean, I know that if the Uninvolved just became enfleshed, they'd still just be stuck with the whole "Oh yeah the Shiplords can still just totally kill you" thing. But, I'm wondering whether the Second Secret can be used to restart and resurrect an Uninvolved species?
I'm also wondering whether a human Practitioner can link to a Marionette, and then try to talk to an Uninvolved. i.e. Can a human bring in a Marionette into this sort of place?
