Was .... the ruler of the ancient kingdom who fought the 20 kingdoms (manga)

I am not sure if it's officially confirmed but with Rocks calling Davy Jones the previous king of the world.

Is it safe to assume Davy Jones was the ruler of the ancient kingdom. And Imu along with the other 19 kingdoms fought him and then turned into the world government.

Also this would make Blackbeard royalty and open up so many new theories