Cold Steel:
I also think it's inescapable that animals have spirits.
I think the adjective you're looking for is implausible.
Add to that the wealth of information in the field of near death studies.
Nothing at all about 'spirits' has been 'demonstrated' by 'near death studies'. People who are near death have an uncontrolled release of neurotransmitters, resulting in 'experiences' not unlike a vivid dream or a drug-induced hallucination. There is zero evidence that people 'have' 'spirits'.