Satan is absolutely a person. All angels, fallen or otherwise, are persons.
God is God. He’s not a “person,” either.
True enough. God is three Persons in one substance.
Are you sure you're not confusing "person" with "human being"? Human beings are persons, but not all persons -- in metaphysical terms -- are human beings. A "person," as I said, is an individual substance of a rational nature.
I would call your “person,” beings. When we speak of “people,” your version says that will necessarily include God and the Holy Spirit. “People” is the plural of “person.”