Dreams are blatantly not random neurological firings, but have no inherent relation to death or the concept of life after death at all.
Near death experiences are similar. The fact that humans have similar experiences when dying is probably not so different from how our behaviors and experiences line up in a multitude of ways, across cultures.
You’re the one dismissing hallucinations as simple or unimportant. Understanding them is crucial to understanding human perception and interpretation at large.
Pretty much all of what psychedelics taught me is that the human brain is soooo fucking primed to see patterns and make sense from anything. Close your eyes hard enough and put some white noise in your ears and see god now.