Maybe sometimes defining can ruin it, as it’s more with “the Spiritual eyes” or in non-verbal images and feelings. Kind of the right hemisphere vs left hemisphere… The two-faced Janus of the human mind. Similar to music, how can you explain a harmony? Have to experience and enjoy, no other way… “Words fail to describe”
The OT says so too. You cease to exist with your last breath. No immortal soul. Maybe it’s so. Of course our mind is the product of the brain, but then it could be a translating device - if you get the brain of a cat then your “soul” is translated at cat level. If you get the brain of a genius, it’s how your “soul” is translated. If that genius’ brain degrades by injury or other aetiology to dementia, then the translation is modified accordingly. Etc. However, the originating “soul” is more than any of its projections. Very primitive approximation of the actual mechanism it could be, or a total fantasy, of course. Probably catching at a straw being scared of death, not accepting finality of life.
There are certain interesting facts, like NDEs or twin telepathy or prophetic dreams etc etc that do happen. Food for thought. Nothing beyond reasonable doubt and everything can be debunked or explained materialistically. So, in no way it’s any proof.
Science digging into the nature of consciousness. Maybe one day there will be a breakthrough. So many things we still don’t understand. Best to remain open-minded in all directions - who knows, maybe one day we’ll stumble upon smth interesting, maybe even smth very new as a byproduct of this quest. Otherwise if we say no is no, we might be closing some exciting doors for ourselves.