"life" is in each cell from the start - that includes the cells in your finger.. every single one of them has "life" ... that thing that makes the difference between alive.... living and dead. If you lose a finger or eye or hand - we do not issue a death certificate even though all the cells in each case are human and they all have all the DNA needed to make "another you". If you lose your brain.. we do have a funeral and pronounce "the person" as being dead. the bible says the spirit returns to God who gave it and 1 Thess 4 says the person is joining those who are "asleep in Jesus".
This is not a fact about SDAs... it is a fact about humans.
Adventists refer to the "breath of life" as the element that makes the difference between a dead cell and a living cell. It is not tied to imagining that first the cell has to "have a pair of lungs". Biochemical "respiration" takes place if the cell is alive. True of every cell in your finger, toes, eyes, hand etc.
God breathed into Adam (who was merely the dust/clay formed into the shape of a man) "the breath of life" and man became a living soul/being. Every single cell "alive" and functioning organs - including a functioning brain.
Had Adam suffered an accident and lost a finger... no funeral for the finger even though every single cell in it.. fully human. Sounds like you want "another thread topic".
Well if you want to "witness" to the idea that you attend funerals for "lost fingers" I leave it to you to make that case.
Adam is not "alive" before God breaths into him "the breath of LIFE". It is that breath of "life" that makes him alive.
Ps 104
25 There is the sea, great and broad,
In which are swarms without number,
Animals both small and great.
26 There the ships move along,
And Leviathan, which You have formed to sport in it.
27 They all wait for You
To give them their food in due season.
28 You give to them, they gather it up;
You open Your hand, they are satisfied with good.
29 You hide Your face, they are dismayed;
You take away their spirit, they expire
And return to their dust.
30 You send forth Your Spirit, they are created;
And You renew the face of the ground.
You want to know when the spirit of man enters during gestation? I am pretty sure a brain is needed but I don't know exactly when during the pregnancy that happens. Certainly very early. And I am fairly certain that zygotes don't have such organs.
This sounds like you needing to start a thread topic on some new thread.