The sentence I'm quoting here is from Rundle, as quoted by Craig, as quoted by you.

Is this something like: When a human embryo is conceived and, eventually, when a child is born, we know it will grow to be *some kind of person*, but we don't yet know what its qualities will be. Its physical body—and, more abstractly, its life—may take any shape. But it must have *some* shape. It has a body and, more abstractly, a life, because that is just what it means to exist as a person.

Is that roughly your understanding of what Rundle is saying here?