Your whole analysis reflects a narrow and simplistic view of history, one that both ignores the long-term American criticisms of communism as an ideology (well before the rise of brutal communist regimes), and that also fails to acknowledge that communism need not be inherently brutal and murderous.
The American intellectual and political tradition has a strong thread of individualism, going back to the classical Enlightenment liberalism of the founders. Many Americans were critical of socialist and communist ideologies in the nineteenth century, well before communism had any real political power and success, because they felt that it undermined the individualism and competitive spirit of capitalist democracy. Americans often opposed immigration from southern and eastern Europe because of a perception that political ideologies like socialism and communism were widely accepted in those places. Hostility to labor unions among some Americans sometimes had its roots in the same ideological principles.
These criticisms emerged well before any organized communist regimes took power, and many in the United States would have been (and were) opposed to communism even in its more benign, non-murderous forms. Indeed, during the anti-communist hysteria of the post-WWII era, manifestly non-brutal and non-murderous policies within the United States, such as public housing and government-subsidized healthcare, were heavily criticized for their alleged communist tendencies, despite the fact that no-one was under any illusion that implementing these policies would turn the United States into a murderous dictatorship.
I’m not arguing that the brutal and murderous practices of some communist leaders were irrelevant to American policies, but they existed alongside a broader and deeper ideological opposition to communism as an economic system. Also, as people have pointed out ad nauseum, the fact that the United States has been willing to tolerate, and even support, all sorts of brutal and murderous dictators sort of casts a bit of doubt on these criteria as the necessary and sufficient reasons for opposing communism.
Also, while communism has often produced oppression, it need not necessarily do this. It is possible for the people of a country to democratically support a communist system. It would be very difficult to make the argument that the Soviet people were in such a situation, but even American intelligence analysts conceded in the 1950s that Ho Chi Minh would have easily (like with probably more than 80 percent of the vote) won a democratic election in a reunited Vietnam. And some analysts of Ho’s oppressive polices have also argued that they came largely in response to concerted efforts to undermine his leadership, sponsored by outside influences like the United States. You can see similar patterns in Cuba, where oppression got worse over time as American-led sanctions and other external pressures made it harder for the Cuban government to maintain power and control.
None of this excuses the oppressive practices of these regimes, but while communism requires a certain amount of authoritarianism and control, it can exist without murderous brutality.