If there is immortality. How do you tell people. How do you show people? Who do you involve? What if syndicates are already involved? What happens next?
Do you have an immortal society and then a mortal? Do you invite everyone who didn’t ‘make the cut’ to come live and learn? That would likely immediately or eventually evolve (or devolve) into a higher and lower, master and slave race. Then what?
So how do you tell the world? Who do you find? What kind of tests can be applied? A show for all? A threat of extinction. Would this be a real test or a real trick?