I'm not sure about this but was Romulus perhaps deified as Quirinus, and before Caesar? On https://en.wikipedia.org/wiki/Quirinus#Deified_Romulus I read "By the end of the 1st century BCE, Quirinus would be considered to be the deified legendary king."
it was a popular form of government around that time, when religious leaders first started gaining power, then got folded into the state, as any institution with power starts to wish to maintain the status quo. And given the extreme, obscene power/wealth/education/health and other disparities that often existed between these kings and their subjects, they practically were gods.
This is missing Guan Yu! The Magnificent beard himself. Chinese Genral under Liu Bei who ascended godhood after his death and I believe is still worshipped to this day