Maybe at first America was a Calvinist society, but it has evolved a bit.
Calvinists have a strong belief in predestination, and they also have felt that God directly blessed those who were worthy. So a cultural attitude developed around those points. Those in want were not worthy of more blessings, or God would have seen to it. Subsequently a person with signs of prosperity would merit respect, and those with great wealth and power merit even greater respect. That’s the origin of the “Protestant work ethic”, the accumulation of things is a sign of blessing.
There is less of a sense of communal mutual responsibility in Calvinist societies and a greater sense of individualism and competition. An attitude develops that if the poor suffer, they were meant to and they have only themselves to blame, intervention is not necessary and it could possibly be argued that it would be contrary to the desire of God. This can lead to a very selfish and self-centered way of thinking, which as a description (I would say) fits modern North Americans about right. We have turned greed and avarice into virtues, and public kind-heartedness into a vice.
However today we as a people have gone far beyond our Protestant cultural roots and now have a sceptical midset, a culture of disbelief that approaches atheism and which cannot be connected to Calvinism. We have retained the selfishness though, it suits us.
+T+