Originally Posted by
Jim Kelly
J'Onn J'Onzz taking the identity of an identical human called John Jones is a retcon. In the original story, the Manhunter from Mars morphs into a human form and muses that his name could be "John Jones" because it sounds similar to his Martian name. He then walks the Earth and decides to become a police detective, upon which he enters a police department and applies for the job. It's a bit remarkable that he got hired on as a detective right away, but given his wide range of powers not that incredible.
Of course it's funny that his Martian name is so similar to a common Earth name. But it's not any different than Katar Hol happening to have a name that sounds a lot like Carter Hall.
The more incredible thing to me was the Kirby Fourth World books where godly beings had names that were similar to Earthly names--like Steppenwolf, Desaad and Kanto.