'Sainthood' in the Shadow Realms
When I was exploring Enir-Ilim, the pillars made of humans reminded me of stories of the 'Hitobashira' in Japan (which literally means 'human pillar'.) Hitobashira was the practice of sacrificing humans before a grand project (such as bridges or castles) to appease gods and ensure the success of the project. In some stories, the sacrifices are entombed/buried alive in the structure as part of the ritual. It was also said that the hitobashira gave the building more structural integrity (with a side effect of the occasional vengeful spirit because not all sacrifices were willing participants.) You can read the wikipedia entry for hitobashira here if you're interested.
Bringing this back to Elden Ring, I felt like this was the most straightforward explanation to what sainthood meant; becoming human pillars for the gate of divinity to usher in a new god. If building Enir-Ilim required a large number of sacrifices, and the shamans somehow acted as catalysts that stuck more bodies together, it'd make sense why the hornsent would hunt them to extinction. It would also make sense why it wasn't just the numen put in jars, it was as many people as they could fit to complete the project.
If this is correct, then it makes sense why it wouldn't matter if the people in the pots were willing or not, their sacrifices would ensure the Gate of Divinity would be made and have their deaths honored in the name of 'sainthood'. The parallels of unwilling sacrifices/martyrdom and direct visual wordplay on hitobashira/human pillars make me think that this explanation is as simple as it gets. It was also shown that in The Lands Between, jar folk were used to bring bodies back to the Erdtrees, so it would make sense if their predecessors in the Shadow Realm also had a role in bringing bodies to Enir-Ilim.
















