Disappointed in one Endwalker Aspect [SPOILERS]

[Kordarion]

Putting someone into a situation that causes them to die is not a natural death. This is the issue.

The people of Etheirys are transcendent beings who live myriad physical lives through reincarnation. In the time of the Ancients they had dense souls and larger bodies which allowed them to live one physical life indefinitely. Even without those bodies, two of them have been shown to live until killed. Those two being Hades and Venat. The two of them have lived 12000 years + However Many years they lived prior to the Sundering. And they could have gone on living however long they wanted to, until they were killed.

Except at no point is this categorically stated, as far as I am aware there are no canon sources that state the ancients have an infinite lifespan. Add to that the game goes out of its way to say that there is no way to cheat death and that all things must die creates the opposite impression, that the ancients can die of natural causes but that we just haven't seen it yet. Therefore Venat isn't putting the ancients in a situation that they wouldn't already experience if not for creation magic hand waving, a state they had to have been in to discover creation magic.

Also your examples of incredibly long lived Ancients doesn't exactly hold up. Venat is quite literally a primal, a god, a being that does not deal with the same type of mortality that you or I or the ancients have to deal with. Doubly so for Emet-Selch who maintains his soul by returning to the in between realm the acsians have that stops them being sent to the aetherial sea when they die and instead allows them to return time after time, its the reason white auracite is needed to kill them.