Gol D. Roger and Whitebeard’s illnesses may have been caused by the Five Elders
The Five Elders are a council of the five highest-ranking Celestial Dragons who act as the public heads of the World Government. They essentially hold the greatest authority over the world at large as far as public knowledge is concerned, although they secretly act as figureheads for the government’s shadow leader Imu, who occupies the Empty Throne.
The Five Elders’ political sway over the World Government, its subsidiary organizations, agencies, and military branches is paramount and near illimitable, including holding absolute command over Cipher Pol, the Marines, and (prior to their disbandment) the Seven Warlords of the Sea, thus controlling two of the Three Great Powers. As of now, it is unknown how the Elders acquired their positions and how long they have been in power, but they are almost always found residing in the Room of Authority in Pangaea Castle
In recent times Oda has been building Gorosei hype and pushing them as very capable fighters which supports the idea that Gorosei are at the very top of the World, literally right under the sovereign ruler of the entire world based entirely on their combat power. I mean Gorosei being combatants should never been in doubt, the very first time we saw them..we saw them with battle scars and one of them weilding what is probably a supreme grade sword Shodai Kitetsu. The Gorosei look like seasoned warriors, with serious looking designs in goofy world of One Piece. Oda rarely gives serious designs to characters unless they mean serious business.. generally this kinda design is reserved for top tiers.
It feels like Oda at one point, looked up every reference for Saturn, Jupiter, Mars, Mercury, and Venus and cross-referenced every mythological pantheon till he created the 5 guys he liked the feel of. They’re supposed to be guardians of harmony so they all work together. Maybe it’s intentional that there are mixed cultures because the Elders are from mixed areas of the world that came together. Who knows(besides Oda)?
Here are the cards of the Five Elders that I created: