Human beings have virtually no value if they are just machines

[Banned]

Biology doesn't think or feel or plan; it just does what it does, repeatably and predictably. In that sense it's akin to machinery.

Biological organisms, on the other hand, are far more than merely the sum of their parts. Life, and whatever purpose the individual derives from it, is an emergent property, not an externally assigned one. Even if you insist that it is such, the onus is on you at least to propose where it is imposed, at what point in the organism's gestation, and more importantly why; since there is no necessity.

These are really good questions.

We may conclude from science that there must be some point at which life, however it is caused, ceases. And it can be assumed that there is a point at which life is introduced.
But as you said, there is no need to look for such a set up. And neither do I look for such a thing, because it isn't necessary.

The power of Life from God, is the cause of every atom, every interaction, every relationship and law in the universe. Whether it is what we call animate or inanimate, there is no distinction. Yet all things created, whether called animate or inanimate, are made to be separate and independent from God, so that the universe can respond to the presence and actions of God.

So I'm wouldn't look for a ghost to enter the body or to leave it. The Bible doesn't support any such claims like the "immortal soul" and other things peddled in religion.

So animals are the sum of their parts, and all their parts are designed.