I've found a bible prophecy and also statement which is interesting regarding the belief of humans never dying at all............
Is 28:10, 13, 15 - it's speaking of a people who are giving command upon command and to them teh word of jehovah is command upon command , measuring line upon measuring line (meetings, field service, etc). In vs 15 it then speaks of them having 'concluded a covenant with death, that they made a lie their refuge. (would never dying be considered that?)
Because Hebrews 9:27 says its appointed for man TO DIE, ONCE, and then a judgement.
1 Pet 1:3-5 speaks of being resurrected to an incorruptible and undefiled
And the scriptures speaking of being born again, if this flesh body/life dies and a rebirth in a new body.
Anyway just someone trying to find a way to make sense and an explanation for tying scriptures and such together and having seen and combined those scriptures, those are my thoughts as a possible truth to what they are saying.