To be a person is a distinct, if not, concept on its own. In an age where ontology qua scientism drives the push of philosophy, we often forget the concrete subject that lives through these experiences. Primitively basic to living through our experiences as a subject is being a person.
The tricky part in philosophy is to assume only so much is suspect in the very question you ask. For instance, in ethics you ask about what is right and wrong action. Thus, this question assumes implicitly: A) moral properties are evaluative of only actions and B) assumes that very level of being a person basic to the ethical experience. Call this the 'received view' of what ethics is. My only point is that being a person is subsumed under the 'received view' of ethics. There is, actually, a deep phenomenological core to describe underneath what the typical 'received view' of ethics.
Contrary to phenomenology, I find that two moves in contemporary ethics have been made about persons, and both an be united under assuming beforehand the nature of persons. The nature of persons are decided before one would phenomenologically look to Following Kant, being a person is expressed through rationality. A person has moral standing only insofar as a person can grasp the form of morality in the categorical imperative and apply it. In consequential formulations, a person is also expressed through rationality, but it is a rationality about the means to satisfy an end that benefits all. This does nothing to differentiate the basic reduction of a person to the rational capacities. A person is only that which can determine the ends of action. Yet, there is more to being a person than a practically rational maximizer or rational apprehender. There are more facets to our lived experience, especially in the ethical dimension than laying bare the basic structural principle of all morality. Laying bare a structure requires that Kant and Mill presuppose the nature of persons prior to describing the structure of morality.
A phenomenology of the person would reject assuming the person outright. The person would have to be defined in such a way that levels of revealing could come forth from personhood itself. For now, a person is that which has subjectivity. Subjectivity is lived through in relation to a world with others, and participants in the lifeworld.