This nation was formed out of necessity, as are all others. In doing so, those who shaped it adopted an enlightened pragmatism, one with a lot of "we" and "common" and other "collectivist" terms.
The fact that the Bill of Rights cam after points to a concern they may have gone too far in the minds of some, but not that we were founded as an "individualist" state.
Codswaddle. Your use of ambiguity aside, America was founded on political individualism. It is quite distinct from your and others continued attempts to substitute for it the strawman of mere individualism.
There is also a vast difference between your use of "collectivist" to insinuate a "group" effort or agreement, and political collectism which is reflective of movements such as fascism, communism, and socialism.
In political philosophy, the individualist theory of government holds that the state should protect the liberty of individuals to act as they wish as long they do not infringe on the liberties of others. This contrasts with collectivist political theories, where, rather than leaving individuals to pursue their own ends, the state ensures that the individual serves the whole society. The term has also been used to describe "individual initiative" and "freedom of the individual." This theory is described well by "laissez faire," which means in French "let [the people] do" [for themselves what they know how to do]. This term is commonly associated with a free market system in economics, where individuals and businesses own and control the majority of factors of production. Government interferences are kept to a minimum.
Individualists are chiefly concerned with protecting individual autonomy against obligations imposed by social institutions (such as the state). Many individualists believe in protecting the liberties of the minority from the wishes of the majority. Thus, individualists oppose democratic systems without constitutional protections existing that do not allow individual liberty to be diminished by the interests of the majority. These concerns encompass both civil and economic liberties. For example, they oppose any concentration of commercial and industrial enterprise in the hands of the state, and the municipality. The principles upon which this opposition is based are mainly twofold: that popularly-elected representatives are not likely to have the qualifications, or the sense of responsibility, required for dealing with the multitudinous enterprises, and the large sums of public money involved in civic administration; and that the "health of the state" depends upon the exertions of individuals for their personal benefit (who, "like cells", are the containers of the life of the body).