The "may not include" requirement rejects the answer itself.
Start with a fully developed human (you, for instance). Moving slowly backwards in time, observe any notable differences in the being shortly before and after the time being examined. (As you said, in or out of the womb doesn't count as it's just a container.) You will find that after conception, there is no point (correct me if I'm wrong) in time where the being before the time is identifiably "not human" and after the time is identifiably "human". After conception, here is no clear point of deliniation identifying the acquisition of personhood. After conception, there is no point where we can obviously bestow the rights of "life, liberty and the pursuit of happiness" upon what shortly before was ostensably a bundle of cells devoid of rights.
To deny a zygote rights demands that you deny an adult human rights, as there is no clear point where you may say "this bundle of cells has achieved personhood, and therefore upon it we bestow rights." Only conception provides the vital clear point delineating person from non-person.
Personally, I believe one of the defining characterists of a "living human being" is a functional brain and nervous system, and so I would regard a 36-week-old fetus quite differently from a 4-cell embryo. Perhaps someone can provide some other defining characteristic?
You compare stages of development some 36 weeks apart. Can you compare stages of development some 36 minutes (or hours) apart and regard them as quite different? This is important, as you attempt to apply drastically different rights to different points in a continuous development process. According to your thinking, the being at the earlier stage may be destroyed on a whim, while destruction of the latter constitutes the worst crime of all: murder. To support such a dramatic dichotomy, you MUST have a clear, natural transition. The only development point of a human being where destruction before is mere disposal, and destruction after is hideous murder is conception.
Maybe you'll appreciate this analogy:
What is the difference between a computer file and its compressed (.ZIP)
form? The latter may be an unrecognizeable jumbled mess, but it is still
bestowed with the same "rights" as the uncompressed form. If you compress
your valuable file, and I delete it in its compressed form, you will be
rightfully mad at me for deleting your file, even though the file was an
unuseable, un-understandable tiny mush of bits. I can construct a .ZIP
file from scratch, knowing what its uncompressed form will be, and I will
be rightfully mad at anyone who deletes it.
A fertilized egg is like a .ZIP file: it is a compressed human being,
fully bestowed with all attributes and rights, and simply awaiting the
de-compression process (which takes about 9 months). A fertilized egg
may be only one cell, but it contains the billions of attributes fully
defining its personhood.
My understanding (open to correction) is that when the brain stops it won't restart. Without a functioning brain, the body is incapable of continuance: breathing and cardiac functions, being controlled by the brain and vital to all other functions, will cease. Other parts may remain temporarily "alive", but as one wag said "I'm dead, I just haven't stopped moving yet."
A key aspect of life is whether the being will generally "continue on" with basic nurturing of proper warmth, air and food. Someone in a coma will continue on as long as we inject pre-digested (so to speak) food into his veins; the body will continue as the paralyzed mind heals itself and often/usually recovers. A brain-dead person will not continue on, as regardless of extraordinary measures (artificial long-term stimulation of heart & lungs) there is no hope for healing or independent continuance. This issue of continuance matches the abortion issue: a zygote, nurtured with a normal food/oxygen/heat source, will continue on and develop into a child. At minimum, if basic nurturing leads to continuance, destruction of the being is murder; that's a minimum definition of personhood.
The problem with pro-abortion and pro-euthenasia people is that they normally want to destroy the being within that range, not outside it in extreme and unusual situations - despite their normal arguments.
Some might say no, because there are still cells, and even whole organ systems, still functioning.
Are they likely to in the near future? A human is generally a redundant, self-correcting system; shutting it down completely may take some time, like water flowing from a faucet from residual pressure after the pump has been turned off. Note that with brain death, the primary functions (cardio and respitory) are no longer controlled and you get a chain reaction of system failures.
There may be cases (I'm not sure) where enough of the brain remains functioning to continue controlling cardio/respitory functions. What about the vegetable fed thru a tube? These are rather rare & extreme cases. My take is that if basic nurturing (including tube feeding) keeps the being "alive", then keep nurturing until a general system failure. Brain dead and on life support seems to be only artificial life: we may force the body to continue, but it's still dead. Even extraordinary measures of life support beyond full brain death will fail, as the body will still slowly and irreversably deteriorate anyway; such a forced continuance faces a still inevitable end.
Doctors & nurses seem to have a good sense of when someone is "dead", articulating or knowing aspects that I'm not familiar with. If the doctor in good faith says "he's dead", he's dead.
At what point in the continuum do we say it ends?
When appropriate nurturing and reasonable repair work (including temporary life support) fail to prevent the body functions (ultimately down to the cellular level) from continuing. After death (whatever it actually is), even the most extraordinary efforts will fail in a fairly short time (days or weeks).
Such works at both temporal ends.
At the beginning, normal nurturing (i.e. normal womb functions, or
care related to premature birth) will sustain the being's development and
continuance toward adulthood. Sometimes despite such nurturing there is
an irreversable system malfunction; tragically, people die. Abortion is
an intentional causation of an irreversable malfunction; that's
murder.
At the end, normal nurturing (i.e. normal feeding, or tube feeding,
or pre-digested food injection) will sustain the being's continuance thru
adulthood. Sometimes despite such nurturing there is an irreversable system
malfunction; tragically, people die. Euthanasia is an intentional
causation of an irreversable malfunction; that's murder.
From conception to death, the being in question is a person and will
continue as such as long as reasonable care is provided. Non-pro-life folks
seek to end reasonable care to destroy the being; their sin is the desire
to end an innocent life, and they desparately try to redefine life to excuse
the evil act.