Castro was a Communist who found it convenient to hide his affiliation.
Despite people being upset about old US support for Batista earlier, it's important to note that the Communist Party of Cuba did support Batista during his first Presidency (1940-1944). Clearly, support for Batista at some point did not translate into permanent hatred by the Cuban people.
The main reason for anti-Americanism in Cuba was the pure dominance of America in Cuba. American companies owned most of the country. The US controlled or supplied almost half of the sugar plantations, the vast majority of the cattle ranches, mines, utilities, oil, and most of the imports. It is understandable that this would rankle a lot of proud Cubans. It created the impression that the US had more influence in Cuba than native Cubans, and in many ways the US did.
I don't think it was particularly exploitative however. Cuba enjoyed a very high standard of living. It was not a poor country; it was not a peasant country. It was a diversified economy whose per capita wealth at the time was greater than Japan or Spain. Living standards were the third highest in Latin America, and almost as high as Italy's. Not a bad peer group.
It was either first or second in all of Latin America in terms of automobiles, radios, and telephones per capita. It had the highest wage rate for industrial workers in Latin America and 9th highest in the world. It had the highest agricultural wages in Latin America. It had the lowest mortality rate in Latin America. It was very well positioned to join the ranks of developed countries in the next 20 years.
This is not the description of a particularly "exploited" country. There were of course problems. Sugar plantation work was seasonal, and the countryside remained poor. All of these problems though were not particularly bad compared to Cuba's peer group, and could have been remedied with a modest welfare state combined with policies to improve economic development - all of which the US would have gladly supported.
While Castro refused to become President early on in the post-revolutionary government, this is a common tactic of Communists. Instead, he did what the Communists always did - take over the critical areas of police and defense, and once having done so remove the anti-Communist politicians. Castro was against democratic elections from the very start. He knew elections would provide a strong democratic credentials to the non-Communists and complicate his ability to take over the government. Castro took these anti-democratic steps in 1959. The nationalization of US companies did not begin until the summer of 1960. Therefore, US reaction against the nationalization could not explain the reasons for Castro's consolidation of power. Cuban officials throughout 1959 repeatedly reported the rise of Communist influence and propaganda. I firmly believe Castro intended to lead a Communist take over from the very beginning, and nothing the US could have done would have changed his mind.