With regard to Fidel and his rise to power, you also have to remember that Cuba was very much a country of contradictions and a "Havana and not Havana" country in the 1950s. Batista had seized power via a coup 7-8 years prior to Fidel's revolution, and the US mafia was heavily infused into Havana. Cubans either had money and lived a VERY nice life in Havana, or they pretty much had nothing, especially in rural areas.
Fidel promised equality, which garnered him enough support to take power. One of the big reasons he became so entrenched after the revolution was because anyone with money fled the country and anyone who might be able to mount a movement against him was killed, imprisoned, tortured, disappeared, etc. The effects of that dynamic are still felt in Cuba today.
During the revolution, Fidel did not "campaign" as a communist. So, while Fidel is usually associated with communism, his ideology as a communist was absolutely secondary to his primary motive which was power. He was an evil, brutal dictator.