@BillRM,
Your questions demand little detailed answer because our life is not as simple as coming into existence through birth and ending with death. Let me go over the Muslim view of creation of mankind and then I will go into different stages of life as described by Quran, Sunnah and explained by Muslim scholars. A lot of these are matters of unseen and I will not be surprised if you don't believe them. That's the reason I asked you to only ponder upon your own creation and death only. Anyways let me explain creation of mankind and different stages of our lives:
Creation of Mankind
The first Man's (Adam ) body was created from sounding clay. His companion woman "Hava " was created from Adam's rib. All his descendant's bodies are created by sperm of man and ovum of women. Jesus (Prophet ISA) son of Mariam (Mary) was created by Allah's word (Be and it is) like Adam but in Mariam's womb. Jesus was a human prophet and not son of God. He was not crucified but taken up alive (Holy Quran).
Allah breathed into the body of man part of His spirit called (Ruh) Soul . When the soul enters the body it becomes alive. When this soul is withdrawn from the body it dies and the body decays, putrefies and is eaten by microorganisms. Every day man experience temporary death at night when he sleeps and resurrects when he wakes up. Allah keeps his soul in a safe place during his sleep. Allah has appointed angels as guardians to the right and left side and allowed Satan to disturb humans. All these facts are described in Holy Quran.
Stage 1. Life in Lau Ho Mahfuz.
Allah created all the souls of the descendants of Adam and Hava who were predestined to come to this earth. Everything about the universes and our soul before and after creations are documented and recorded in the tablet (book) board in heaven (Lau Ho Mahfuz).
Allah once asked all the created souls, "who is your Lord?". All the souls said "You are our Creator our Lord". But souls forget the covenant when they descend to the earth. Some have faint or vague memory of Allah (God) in the inner core of the heart. At times of life threatening danger man will automatically shout "Oh God !". But who is that God? If no one tells him he will not know. At that time they usually do not address false gods. They usually point up to the heaven and say Almighty God meaning ALLAH.. If they say that many times they will forget false gods. That is the inner instinct of Humans.
Stage 2. Life in the mother's womb.
The soul is sent down to this earth into the body of fetus developed in the mother's womb and the fetus becomes alive. The fetus was swimming in the amniotic fluid inside the uterus like a fish. It does not breathe air. The fetus was fed by the blood through the placenta of the mother and supplied to the body of the fetus by means of umbilical cord. In pregnant women there is no menstruation until the baby is born. Do we remember how we lived 9 months inside the mother's womb?
Stage 3. Life in this world.
At the fetal age of 36 to 40 weeks (pregnancy) the baby is born. The baby breaths the first time and cries. Whereas the nurses, friends, parents and relatives laugh, are happy and praise the baby. When the same baby become old and dies, the relatives and friends cry. The newly born baby is clean, innocent , free from sins, grows, develops , learns and is brought up in Muslim families or in non-Muslim families. The soul in the baby forgot Allah and the promise (covenant) given in the heaven that Allah is his Creator and Lord.
All souls have to taste death. When the soul leaves the body, relatives and friends cry. The soul of man will be extracted by the angel of death either gently or roughly when the time is ripe. Therefore this stage 3 is very important testing ground for human being and next stages depend on how we lived this stage. Did we recognize our creator and followed His commandments or did we just ignore all the signs and followed this material world and our desires.
Stage 4. Death.
After the soul is drawn from the body Allah keeps it in a place called Alam Barzaak. Good people's soul are kept in a good place and bad people's soul in a bad place until the Judgment day arrives, when everything is destroyed except Allah. There will be resurrection of all Mankind
Stage 5. Resurrection on the Judgment day.
All souls will get up from the graves. Obedient souls will go to paradise for ever. Disobedient souls will go to hell for punishment. Those who ignore or reject or refuse to believe Allah and who worshiped false gods rather than Allah, The Creator , in this world , will go to Hell forever in the next world.
Stage 6. The end stage for disobedient soul is to enter Hell fire.
Stage 7. The end stage for obedient soul is peaceful to enter paradise in the form of new creation with different forms. Allah said that it is easy for Him to do so (Holy Quran). In paradise they will be free from sickness, illness and will at all times be healthy, clean, peaceful and satisfied with provisions, no ageing, to dwell in forever. This is because Allah is satisfied with the soul who is obedient to His Divine laws and the soul is also satisfied with Allah.