I wouldn't be surprised if Archie is kept under wraps for a while. It might be this is how they will with him be as long as they can
He didn't get a title. Harry has never seemed to me he was very keen on being a royal to begin with
It might stem from his mothers death. He was very young when it happened, and he might not want that type of attention for Archie
It is different for William and Kate. They are in direct line for the throne ,and their eldest Prince George, is heir apparent, or presumptive, I am not sure which is the proper definition