Defining human life is simple.
1. Is it alive? Yes
2. Is it of the human species? Yes
3. Is it the entirety of an individual, defined by a future separate from his or her mother and unique DNA? Yes
Then it's a human life
None of this "it's an embryo, not a human."
An embryo of what species?
None of this "it's not a person so it doesn't count"
An abstract concept of personhood cannot be used to determine whether something deserves to live or not. That's a slippery slope. If you cannot tell me exactly what personhood is and when exactly it starts with concrete evidence, then it is another arbitrary category.
There is no evidence to suggest anything other than "personhood", or being a distinct individual, is something everyone has from the start, not some extension you collect at some point in development.
The DNA of a zygote has every piece of information about the child and adult he or she will grow into. From gender, to complexion, to colour of their hair, to so much as parts of their personality. It's already all determined at the moment of conception, setting them apart as a unique individual worthy of love and protection.