Fidel was a true believer in Marxism since his days at the University of Havana but he had to ally himself first with people (not all of them Communists) who despised the Batista dictatorship. It was clear from the outset Communists were the dominant element in the Revolutionary leadership and eventually imposed their totalitarian rule over the island.
But before all that, Fidel was the Revolution and he led it and not the Communist Party which was only formally founded in 1965. Fidel was the last charismatic caudillo in Latin America. His place in history is secure next to Franco of Spain. We will never see his likes again in that part of the world.
Fidel was a true believer in Fidel, and that’s it. The Communist in the family was Raul, and he preferred Chinese Communism as did Che. The Soviets didn’t like them and they didn’t like the Soviets, but they had a common enemy.