Angels and heavenly beings and human beings can be called people and sometimes translations of scriptures call them men. Many are man-like as distinct from a serpent-like or gargoyle-like being and there are angels who can appear like men. So if you see one you might simply say you saw a heavenly man. Yet the Lord before He was made flesh was called Son of Man or one like a Son of Man which implies He gave impression to those who saw Him (those blessed by God such that God gave them sight of Him) were somehow aware He was more human than angels who appeared human. This is what Jesus meant it seems by explaining He is this Son of Man - He existed since aeons past but more human than man-like angels so He is a man for mankind: The human man for mankind.
