Questionable ethics - Living Memory

[Infindox]

But they're the same thing; sentient synthetic life-forms. AI with self awareness, the ability to change and adapt, with desires and dreams, with emotions.

Actually I think the Omnicrons and the Endless are two different things.
The Omnicrons evolved to the point they are seen in Ultima Thule and are a sort of "evolving machine". They can learn, grow and adapt. They are actual life forms, just in a non flesh body.

The Endless do not evolve. All they are is memory data. They don't really learn anything being in Living Memory and seem to exist to be a coping mechanism for Sphene. They are the idea of "memories make people/ideas immortal" to the negative extreme. They are unnatural.

[AnotherPerson]

They aren't, the golden city shadows are simulations of people. They're coded to act in a way, to have specific desires, to have specific dreams, to have specific ranged of emotions.
They're snapshots of people who used to exist.

Not entirely simulations. In the final cutscene after Interphos trial, Sphene mentions she was recreated with a portion of her memories as her time as an Endless (so not as a Queen of Alexandria but as a Queen of the Endless) - except this time she's no longer bound to Preservation's requirements for saving her people at all costs. At that point, we saw the true 'Endless Sphene's behavior' and it was pretty much the same thing, but no longer opposing us and making peace with accepting her end and handing us the Interdimensional key. A ruler who is no longer carrying the burden of preserving all of Alexandria. That's her own emotions and this time, whose emotions were not influenced by the memories of the original Sphene. From this, we can see even if the Endless have memories of their original selves, they still make memories afterwards. Memories that end up defining who they are in this lifetime. The only difference is that this time, Sphene is no longer bound by Preservation and has free will like the rest of the Endless.

The same applies to Endless Cahciua. She originally wanted to escape Living Memory but got stuck in the dome. We later learn she spent years trying to figure out a solution for the Endless when scouring Preservation's records, but ultimately resigned herself to erase the Endless because she couldn't find a solution to the energy issue. It's here we can see Cahciua made a decision between Duty and morality. Of course she would've preferred to continue living, but she didn't want to do that at the cost of harming another person due to the energy shortage. Otherwise, she would not have bothered to search for a solution for years. How would she have reacted to the people she met in Living Memory? It's an entirely new place for her to explore - which mean she encountered and interacted with plenty of different people. There's no such thing as a static simulation when you keep on introducing more and more people into it, but also let different people's lives run their course. If she was coded to act in a certain way, I'm quite certain they wouldn't allow desires for the destruction of the terminals. It's clear to me that there is free will at play here.

That's why I look at them more like clones that are separate from the original. They could have similar life experiences, but their choices would then diverge based on the environment they are living in. The Tenacious Tour Guide from the blue sidequest Well-wishing on the wishing well also mentions he was proud of staying true to himself and would like to be a tour guide in his next life (makes no sense because he is already a tour guide in his current life). All those instances are signs that the Endless have their own free will and memories to say such a thing.

The copy is ultimately just another clone. It's not the original. Clones on the other hand are still alive. It can be argued that the existence of clones are unethical if they're meant to replace the original, but they're alive and can feel emotions as any other being. The sustainability of the Endless was the real dilemma. That was the real problem - the problem where we never get a chance to address because we're "out of time". If we could solve the issue of not requiring Life Aether (and thus allowing souls to return to the Aetherial Sea), none of this would have been an issue.

Actually I think the Omnicrons and the Endless are two different things.
The Omnicrons evolved to the point they are seen in Ultima Thule and are a sort of "evolving machine". They can learn, grow and adapt. They are actual life forms, just in a non flesh body.

The Endless do not evolve. All they are is memory data. They don't really learn anything being in Living Memory and seem to exist to be a coping mechanism for Sphene. They are the idea of "memories make people/ideas immortal" to the negative extreme. They are unnatural.

You forget Endless Cahciua exists. She adapted to her surroundings. She aimed to escape Living Memory because she wanted to continue exploring new zones. Her determination drove her to learn about robots and computational systems to pilot a robot outside of Living Memory. She built an entire resistance when she learned of Zoraal Ja's plans. She looked through Preservation's records for years for a solution on the energy shortage for the Endless. When we reached Living Memory, she adapted to the circumstances of Sphene taking her time to prepare for Interdimensional Fusion to tell us to shut down the terminals because this is the most opportune time to do so. In the end, she was also able to spend her time with Erenville and see him grow up with her own eyes, thus no longer having any more lingering worries. Out of all the Endless we know, I'd say she evolved the most.