The US constitution is every bit as inadequate, contradictory, and ultimately destructive as the religions just mentioned. It is the source of America's class system and warmongering behavior.
In the context of the current social organization you are completely correct. This document was written by white people for white people. The authors were all self-aware racially and acutely aware of racial differences. Whites (Europeans), Blacks (Africans) and Indians (as proxies for Asiatics) all received separate Constitutional treatments. It was written for an American white nation. In the Constitution Indians were specifically recognized as inherently belonging to Indian Nations that were separate from the 'American' nation.
Here's a representative opinion from Thomas Jefferson concerning slavery, blacks and whites:
"Nothing is more certainly written in the book of fate than that these people (i.e. blacks) are to be free. Nor is it less certain that the two races, equally free, cannot live in the same government. Nature, habit, opinion has drawn indelible lines of distinction between them."
Jefferson's views of Indians were more complex. Jefferson considered some tribes (biologically closely related groups of people) to be civilizable, such as the Cherokee. Others he considered would have to be "driven into the mountains" because of their inherent incompatibility with white standards and modes of life. In all his cases his test of 'civilizability' was ability to conform and adhere to white patterns. The jewish concept of 'Melting Pot' appears nowhere even in Jefferson's thinking.
Had anyone told the Framers that 200 years later there would be an attempt to govern blacks, yellows and whites in a single polity under principles clearly written only for whites, and that this would even be presented as an ideal, the authors would have looked at such a person as being insane. The present instabilities and distortions you rightly complain of, such as international war-mongering and imperialist adventures, did not appear until long after the racial distinctions clearly codified in the original document were broken down.
It was also the intentional mixing of two races within the same territory that paved the way for the appearance in practice of the first permanent American class system. Where after all did the 'Planter Aristocracy' appear? The mono-white North or multi-racial South? What was it based on and sustained by? Ownership of and exploitation of one race by another.
The original Constitution contained a number of measures designed to prevent the emergence of intra-racial classes. The Negro Question was recognized even by most of the Framers as the biggest single flaw in the document. But 'class' systems are not something that can be prevented when races with inherently different skills, abilities and affinities are mixed together.
Of interest is a related question. Which side in the Civil War did local American jewry back most strongly? The Confederate South, of course. Revelations of the Method concerning this are increasingly appearing even in 'mainstream' media such as the Washington Times. These revelations include the deep jewish involvement in the slave trade; the greater political emancipation of jews in the slave holding South; the external financial backing of the Rothschilds and the British Empire for the Confederacy and their pre-war involvement with Secessionist conspirators; the Southern economic adherence to principles of "Free Trade" and opposition to national tariffs; the opportunities for the International Race (or non-race) to mediate this trade (not emphasized); the largest jewish community of the time thriving in the port of Charleston, South Carolina (site of the opening cannonade).
In other words the interests of the Old Jewry in socio-economic conditions approximating the Confederacy (mixed race populations, 'free' international trade) appears not to change. Whether called 19th Century 'Slavery' or 21st Century 'New World Order' the features are the same. These are high levels of cross racial immigration, a weakening of all borders, the creation and sustenance of rigid class hierarchies and consequent wage squeezing on the working classes.
What was Abraham Lincoln's real thinking? He was opposed to slavery towards the end. But he was more opposed to disunion, the growth of banking and finance capitalism (Mammonite-ism) and equally opposed to race mixing. His concept of Negro Emancipation included Deportation and/or Repatriation. The proto-National Socialist aspects of Lincoln's overall approach to restructuring America are seldom commented on.