Still stand by the notion that the Elders are immortals from the void century, probably generals or whatever that fought to bring down the ancient kingdom. I have a hard time picturing a way for the story to explain their scars, the guy with the sword, and their overall attitude (not to mention the fact that they looked exactly the same way during the Ohara flashback), if they have been born into the highest political sphere from the get-go or even are simply CDs from the highest-ranking families. Oda has made a point of constantly emphasizing how the CDs isolation from the world and position has made them spoiled, entitled pieces of shit, which is completely anathema to how the Elders are portrayed.
Also I think it's weird to think the "gray morality" that some people think they displayed is somehow eroded by the existence of one leader they take orders from. It's as if Imu himself necessarily has to be an Orochi-tier villain, he couldn't possibly have any agency or complicated thoughts about the world, right?