From an alternate Earth, a rabbit named Hoppy was struck by lightning, and became Hoppy the Marvel Bunny.

One time, Uncle Dudley was really struck by the magic lightning, and truly became a marvelous Uncle Marvel. (Yeah, I know he's part of the Marvel Family... so I don't know if he counts or not.)

The Lieutenant Marvels, of course, were hit by lightning. I don't remember for sure if it was ever established if they were cousins of the Batsons or (as I recall) just three other boys named Billy Batson.

Sivana named himself Captain Sivana, but that quickly escalated to self-sobriquets of Major Sivana, Colonel Sivana, and General Sivana. Shazam wasn't there to tell him his new identity was Captain Thaddeus (and let's be honest... would Sivana REALLY have listened? :)

As for there never having been any Black or Asian Marvels, well... there were numerous stereotypes throughout the Golden Age and Fawcett Comics. Cap's valet Steamboat was a regular character for a few years and blacks in general in the books followed that depiction. There were wartime Japanese villains such as Nippo. 

And there was a Captain Nazi-style super-foe called Captain Nippon who showed up a few times in Captain Marvel Junior's book. He wore a green costume with epaulets, similar to Nazi's outfit, but was also outfitted with pointed fangs which he could use to bite and chew his way through anything, including the foundation supports for the Empire State Building. 

Also, Steamboat once gained super-powers of a sort after a trip to a hypnotist and fought crime in his long underwear and a tattered cape as "de Hahlem Mahvel." 

So, it's not as if there were never any super-powered Marvel-style racist caricatures in the Fawcett books.