[the_third_wave]

No, it isn't. Those principles are things to be strived for, both when the words were put on paper as well as now. The fact that not all of those who put those words on paper totally embodied all of those principles does not make them any less worthy, they are a guiding principle after all - not a description of the state of the nation or the world in the 1700s. Under that guiding principle the USA has gone from a state which inherited slavery to one which, together with the United Kingdom, abolished slavery as well as the trans-Atlantic slave trade. While this did not totally end the practice of slavery - it existed long before the first slave was brought to the shores of the colonies and kept on existing long after the last slaver was boarded by the Royal Navy, indeed it still exists today in many countries in the middle east, Africa and parts of Asia - it did set in motion the cultural shift which made the concept of enslavement to be something which is unreconcilable with democracy [1]. There have been several ugly episodes in the history of the USA after slavery was abolished but this is one of the few cases where the arc of history indeed has tended towards justice. The wheels of justice may move slowly but move they do - unless obstructed. This is why the rise of identity politics - which aims to derail justice into ${identity_category} justice - is so harmful since prefix-justice is not justice.

[1] this did not use to be the case, the Athenian democracy had no qualms about slavery