A person loses consciousness (from extreme fear, for example), but it returns. The body without consciousness exists and lives. Haven't you seen in movies how heroes ask to be killed if they turn into a "vegetable" (i.e., unable to think or move, just existing)?
So, according to you, consciousness transfers from one person to another based on the principle of "what is lost in one place is gained in another"?...
Consciousness develops with a person and dies with them. Simply existing is not living; it's being dead, but not physically. It's impossible not to think; you can think at different levels, from a child to an elder. From unintelligent to a philosopher and back.
Regarding a body without consciousness:
A lifeless body exists, but a living one does not.
They turn into a "vegetable" when the body's life force is depleted, but it clings to life with all its remaining strength.