so children up to the age of, lets say 4, can just be disposed of because they most likely won't be able to make it without their parents. That's how I read that argument.
A mere zygote does not equal a human being. It's not a human until it can function on its own without the mother. So, up until about the 8th month, it's not a person, it does not have a soul. I'm not 100% pro-choice, but your argument just slightly irks me.
I also will just play off of definition here and state that YES a zygote is human. 46 chromosomes in each of it's cells that codes for everything human. Person is what we're looking for in this case.