So Amenadiel asked God once, if Charlie was mortal, and god answered "it would appear so". A very criptic statement, but it is supported by Charlie getting sick and displaying no powers whatsoever.
On the other hand, Remiel came to earth in season 4, because she sensed a "new celestial". Her assumption was, that Lucifer fathered a child and wanted to take it to heaven. Giving that, her ability semms to be some kind of "hunters sence", where she can detect living beeings and know what and where they are.
These two things seem to be contradictory, but I have a theorie.
We know that angels self-actualise. Also, angels popped into existence fully formed, with adult bodies and an ego. I think Lucifer said this to Linda once, when he joked about angel-school. At that time, Linda asked if the powers formed the personality, or if the personality formed the powers.
Charlie is a baby. It is more that debatable if he already has an ego, personality or even conscience. Those things are formed through experience, by living life and learning, when the mind develops. There is nothing to self-actualise, because he doesn't have a sence of self yet, that he could actualise. I believe that Charlie was born with a human body, but maybe his angel-powers of self-actualisation will manifest, when he gets older and his mind matures.