I've thought about it some more, clearly the One Piece isn't something Roger could use, because he was able to otain it but not do what so many speculate would happen when one finds it, which is to dismantle the World Government. & if you are to believe that it has ties to the ancient kingdom & Joy Boy, & that it requires one who inherited the will of D, then Roger should've been able to use it to take down the Gorosei. There's no knowing for sure whether all the D's are actually what they should be, but Roger did exhibit some extraodinary traits that aline with what Luffy can do, so we can assume he's a legitimate D. But why did nothing happen when he found the One Piece? Did he even find it or is it something he collected pieces of in his travels?
Let's assume that the One Piece is something only a D can use & is indeed linked to the ancient kingdom, then we can assume it's some kind of weapon or power than requires one with the proper lineage to activate, maybe even a seat of power. But that isn't likely because a lot of clues point to the ancient kingdom being a peaceful people that wanted freedom for all, so no weapons, & it doesn't seem likely that someone like Luffy would want a position of power like being king or something like that. Which brings me back to it being some lost knowledge that when revealed, would make the existence of the World Government unnecessary. But that doesn't sound right to me either but it's the better sounding of everything I'm able to think of.
