When I brought up that I could only remember back to when I was 5, I was just showing that there must have been some point, post-delivery, before which people can remember their lives. I'm sure it varies from person to person, and that would be part of the impossibility of having a universal definition of personhood occuring in those early years.
I'd like to hear more of the 'potential' argument. An acorn or fetus may be biologically mapped to become a tree or person, but that is due to a natural biological cycle of reproduction. I have the 'potential' to become a millionaire, does that mean you treat me as if I already was a millionaire?
I happen to believe in an individual human spirit. I cannot prove the moment when that spirit is present with the indiviudal soul. That leads me to search for supporting evidence of when the soul is present and thus assume the parallel presence of the spirit at the same time, to be safe.
I can make a very good case for the soul being present at the zygote age. You may draw conclusions from that ... I do not accept the 'potential' when there is already an organism present at zygote age. Potential is what sperm and ova are.
Pick up a real acorn and carefully open the meat of it. At the dividing line of the two halves you will find a small oak tree already in evidence. The same can be done with any peanut in the shell. An acorn has within it a real already visible oak tree. People come up with lots of foolish stuff when trying to dismiss truth in order to support what they want to be true but is not true. I would refer you to the specious term 'pre-embryo' This falsehood has sucked in no less than Orin Hatch.
You may have read the term 'fertilized egg' when referencing a petri dish embryonic aged human. Fact is, when fertilization occurs there is no loger an ova or egg, there is a distinct new organism, even though the zygote and morula ages are spent inside the zona pellucida of the original ovum. Even in this age spent inside the original cell membrane of the ovum, the new individual life is differentiating cells to allow for implantation and formation of the first organ for survival of the living organism. The problem with most falsehoods perpetrated to support killing embryos for their body part, they try to alter the truth to fit their desired paradigm, and that can be deadly.
The first application of embryonic stem cells used to treat a Parkinson's patient killed the patient because the stem cells harvested contained cells to produce the body for life in the air world AND cells for the placental encapsultation. The embryo had already differentiated cells yet those pushing a falsehood claim embryos are undifferentiated cell masses from which stem cells must be harvested for treatments and research.
In short, use a simple test to measure a notion regarding the earliest ages in human life: is the object of the discussion an organism or merely portions of a future organism; is there an actual organism present? If the object is a human organism, he or she (and the sex can be determined at earliest age) is a human being at earliest age in a lifetime already begun. Growth and metabolism evidence life and that is active manifestation of the soul of life, so assume the spirit is there also, unless proven later to be inaccurate. [That is your cue to try and raise the winning argument. To which I will reply, 'would you shoot into a box where at least one child was playing, even if two children may be in the box?]