a clump of fetal cells is the textbook definition of dependent and inseparable. you're otherwise projecting what they might become if everything goes well, not objectively perceiving what they are in the present. if we projected every human that way, we're all dead, and therefore worthless.
neither our subjective nor objective experience of those cells today is equivalent to that of any human being around us. you just can't get to the conclusion you want with only biology and objectivity, because your key premise is neither an objective nor a biological axiom.