Also; I'd like to address this misunderstanding:
...Only that there doesn't appear to be a need for one(for us to exist).
Absolutely not.
If subjective capgras shows us anything it is that the emotional recognition of our self - the
feeling of us being inside of ourselves - is absolutely critical to our functional level of sanity.
Removing it, the sensation from which a people interpret as being a soul, absolutely cripples an individual's perspective on reality and in most cases causes the individual to absolutely reject all of reality entirely - not just their own self.
When humans don't
feel inside of their own body, then the brain will reject all of reality instead of rejecting the signal telling it that it does not
feel inside of itself.
That is the opposite of not needing - that is critically and fundamentally requiring.
That people call it a soul and create metaphysical constructs around the sensation is a cognitive byproduct of this fundamental requirement of self-identity.
What we don't require is the metaphysical description of the emotional identity of one's own self identity, but we very much need the emotional identity of one's own self identity.
On the other hand; if you meant that the person can physically still be alive without feeling like they have a soul (as explicitly claimed by some individuals with subject capgras), then yes - we can physically function without the emotional recognition of our own self identity.
However, it is not a functional existence and requires assisted living.
It is like claiming that one doesn't need the prefrontal lobe to exist.
No, the human being as a thing doesn't need it to physically continue pumping blood through the body and firing neurons around the brain.
However, if what we mean by "exist" is AS the identity the individual PREVIOUSLY understood themselves to be, then no; an identity cannot "exist" as it DID without the components which permitted the formation of THAT identity...which is why they all claim to NO LONGER exist as THEM.