It is strange to consider Thomas Jefferson's writings when speaking on traits of the American. Jefferson never wrote directly on the topic of the general character of the American. It was he, who was more responsible for setting the parameters of a society which would fulfill the ideals of what would become a part of the American character. He knew that liberty and equality could not exist in a hierarchical society. He also was aware that a society which was primarily production oriented, bound together by interdependence on those who controlled the the financial resources would put to much power in the hands of a few. A society of farmers, he believed, could support a society based on individualism and not conformity. This view, read by early Americans, led to the view of the American being an individualist and not a conformist.
In order to be considered a nation the people have to be united through a series of common qualities and values.
The most important of these is the quality of individualism. To be an individualist ties in all the other essential qualities of being an American such as the right to create your own destiny. The opposite of this value is conformity, an essential trait of those under a hierarchical system such as a monarchy. Conformity is not only seen as a trait of the subservient but also a destroyer of true democracy.
Individualism was a trait actual selected for by the very processes which led a certain type of person to come to America. The non-conformists were people who would not allow themselves to be goaded into directions the monarchs of the old world wanted them to follow. This type of person has to be and individualist because a conformist would just remain in the old world content to follow the lead of others. The effect of settling a wilderness also was a contributing factor to the formation of this trait. Being isolated from others and most of the time totally dependent on yourself or the small band to which you belonged for all your needs is very conducive to further development of individualism.
This individualism could only thrive in a society such as the one Jefferson conceived. As society develops and the populations become concentrated interdependency grows killing off the independent spirit. As society changed from an agrarian one to production oriented society, starting in the early 1800's, Americans became dependent on others for things which they no longer produced as a family unit. If you are working for someone else and dependent on pay from them to buy things you can't or don't produce you have lost your independence. Once independence is lost you become just a cog in the machinery of society.
Majority rule, which Jefferson espoused, was one of the great destroyers of this individualism. It is an example of American culture being shaped by the forces of democracy. Even though you might think rule by the majority is conducive to individualism it is not. Rule by the majority fosters dependence on others because of the tremendous pressure it puts on the minority to conform to mass ideals. Jefferson, a great believer in the individualistic spirit, actually sounded its death knell with his democratic ideals of rule by the majority.
It is in this that you find the greatest ambivalence in his writing. Jefferson included in his desirable traits two traits, which on the surface look completely compatible, but in reality are not conducive to each other. Rule by the majority fosters interdependence between the majority and minority. The majority has more control on society then the most despotic monarch can have. Majority rule acts on society both physically and morally exerting tremendous pressure on the individual. A monarchy can only act physically to control and subjugate the individualist. Americans are forced to bow down not to the power of the monarchy but instead to the much greater power of a majority of his peers and is required morally to not only follow but to actively support their wishes. Jefferson's writing was widely read and acted as a trigger in society. He put into motion the very forces which destroyed his ideal of individualism. The democracy in which he was instrumental in fostering destroyed the primary characteristic he sought to preserve. Individualism and rule by the majority, both included in his writings, were actually two opposing forces, each working to subjugate the other. Democracy will not work in a nation of rugged individualists. The very foundation of democracy is built on cooperation among a wide variety of individuals. This is very conducive to the creation of conformity and very antithetical to individualism.
There are forces at work today that are far stronger then those at work in early America which forces and rewards conformity. While the American public likes to think of themselves as rugged individualists we are actually a nation of "Baa Baas" sheep following the ram of government. The idea that we are actually a nation of conformists is actually very repugnant to most individuals. As a society grows more complex it grows proportionally more interdependent. Unless we have a cataclysmic event such as a meteor, nuclear war, or invasion of aliens we will continue on this road to conformity no matter what our original founders intended.
You can see this unintended ambiguity of Jefferson's in almost all of his political writing. Even in the Declaration of Independence when he speaks of the "unwarrantable jurisdiction over us." by a monarch he does not realize that this will be replaced by the unwarrantable jurisdiction of the masses also known as the majority. In his letter to John Adams, 10-28-18 13, the setting up of a system of schools is the creation of one of the strongest forces of conformity. If you have a system of nationwide like minded schools you have created a method of bending a majority of minds in the same direction thus not only creating conformity but also insuring its continuance on a grand scale. Further he proposes further education of those who conform to the schools ideals of a good student thus insuring the creation of a legion of future leaders and controllers who would be of the conformist ilk. His idea here of a creation of like minded wards would "enable the state to act in mass," thus creating even further conformity across this land.
None of these ideas should be considered to be a slam against Jefferson, a man I have respected since youth. They are just the unintended creation of opposing triggers in his writing. Being read by such a huge segment of the population in early America led to these triggers being inserted into the formation process of America and thus having a strong effect on the way our present culture evolved.