As a natural US citizen it took me a while to understand what I was taught about US history in grade school was not entirely accurate. US independence was about corporate interest. The land barons and industrialists did not want to pay taxes to the crown. That was the offense that led to a declaration of independence, everything else was cursory.

At most half the American population was in favor of independence. Those that spoke against independence were labeled as Tories and terrorized into submission (sometimes horribly). The people with money and influence led a campaign of terror against them. If they had actually held a vote and went with majority rule, it's likely we'd still be a British territory.

As far as the constitution, the authors did not consider other races as equals with human rights. When they said, "Liberty and justice for all." they were talking strictly about men of European descent. Even white women were not considered in the term "all". This is how the genocide of native people and slavery was justified. The people suffering these horrors were considered animals same as livestock. This ideology originated in the major Christian churches of the time which were all run by, you guessed it, men of European descent.

Of course in modern times we know that human genetics are one of the least variant of any species on the planet, but back then they relied on the Church instead of science. You can thank those guys for over a millennia of dark ages and unjust human rights.