Life does not begin at conception. Or at birth. Life is continuous from God Said. An individual HUMAN life begins at conception. The egg and the sperm are not dead nor are they inanimate substances like iron or sodium chloride. They are living protoplasm. Life is in them.
I used to explain it thus t college audiences: whether you believe the human race began 6,000 years ago or 1.75 million years ago, geneticists are convinced that the human race all descends from a single ancestral couple. Human life began with that couple. It is transmitted to a new generation every time fertilization occurs.