Despite what religion may say, I am convinced that what we call angels have had at least one physical incarnation, which may well have been on a place other than earth. Sources like the Urantia Book will indicate that they are simply ET's who allegedly have much more wisdom than humans, at this stage in our development. The problem is that they mix them up. EG: there is an entity they call Christ-Michael, who they claim is God's son and the one who came to earth and died on a cross, not Jeshua.
From what I understand, there are some who can alter their vibration so they are visible to our physical sight but not all of them. I wonder if "celestial beings" would even inhabit a physical planet?
Unfortunately, most people have a tendency to believe what their church tells them and do not go looking for other references. There are numerous types of beings out there, beyond the barrier of this reality and angels are only part of this group.... but they are of spirit, not physical.