Can a sperm or egg differentiate into a human being?
Absolutely, given the right conditions. A human skin cell could be made to grow in to an entire human given the right conditions. A fertilized egg cell will only grow in to an entire human given the right conditions. Your cut off it completely of fertilization is complete arbitrary and not based on any scientific data. The only difference is the number of chromosomes.
Let's make it simple - is a fetus human life? What separates a fetus at 8.5 months of a development and a baby that is post birth by 1 day? What makes it okay to end the life at 8.5 months, but not post birth by 1 day.
Please point out where I have ever argued for abortions at 8.5 months. We are talking only about abortions of non-viable fetuses. Creating strawmen like this only weakens your argument, as does using clearly hyperbolic terms like pro-abortion and celebrating abortion. Thinking that women should have a little bit of bodily autonomy is not the same as celebrating abortion.
Exactly, this is my point, similarly, a zygote, embryo, and fetus have the capability for consciousness, which is why it is a tragedy to abort them.
Not before they are viable they do not.