It's very annoying, that the same Hebrew word can be used for 'boy' or 'servant'. (Same with 'girl'). Annoying, because when drawing a picture it's helpful to know roughly how old someone is. At least are they an adult or a child.
I suppose it's the same as in American slavery, where a slave would be called 'boy' no matter his age. Or, indeed, a stable lad, who can be a 'lad' till the day he retires.