I don't know about short and fat but he was a negro. According to the 1940 census (where his occupation is listed as cook on a steam ship and his race as Negro) he was 37 years old and was born in Virginia. He lived with his wife, Ernestine (age 32) and three daughters (ages 4. 3 and 1) at "2230 Seventh Ave", New York City, NY.
When the State Department was trying to notify his wife after his death, they first sent a letter to "2228 South Ave" which was returned undelivered. Looking at Google Maps, it appears that 2228 Seventh Ave is a large multi-story apartment house.
Many of the pages in his file relate to the calculation of the wages he had earned on the voyage, a list of his personal effects, etc. I appears that his personal effects may have remained on the Nathanael Greene until it returned to Great Britain. At that point they may have been brought ashore and it is unclear who was responsible for getting the effects back to the family, the State Department?, the Steamship company? Among the effects is listed "Seaman's Identification", which would be his Z-card. Too bad they didn't make some sort of photostat of it, as it had a lot of info on it. Here is an example of Z-card:
https://selfdefinition.org/rose/rich...-card-1947.htm
I'll see what else I can find.