From a biological point of view, a human’s life doesn’t begin at conception, at least for two reasons.
First, the two cells that merge at conception are already live. The cell body of the sperm disintegrates after fertilization, but the egg continues to be a biologically living cell. The eggs starts to behave in a new way, indeed, but calling that change as “a new life” is an arbitrary and often religious interpretation of biological processes. From a biological point of view, one can say as well that human descendants are blossoms of blossoms of the original egg cell.
Second, the fertilized human egg is far from life as it cannot live alone, independently from the woman’s body. If you biologically separate it from the later, it ceases to be exist. And its dependence on the woman’s body is totally different, e.g., from the dependence of a newborn baby on their parents because a baby can be fostered by other human beings but a human zygote or an embryo cannot exist out of the women’s uterus. So it doesn’t have the quality of biologically independent human life.