The Declaration of Independence and the US Constitution are two very different Documents written at different times by not necessarily the same people for different purposes.
The Declaration says, we have had enough of being governed by the King of England and we thirteen colonies declare our Independence for the following reasons. The stirring terms such as: “We hold these truths to be self-evident, that all men are created equal, that they are endowed by their Creator with certain unalienable Rights, …” are used to gather support for the action among the populace.
Having won the Revolutionary War, the former Colonies, now 13 States have to organize a system of Government for the new country: The Constitution is that system of Government.
The Preamble lays out why it is needed:
“We the People of the United States, in Order to form a more perfect Union, establish Justice, insure domestic Tranquility, provide for the common defence, promote the general Welfare, and secure the Blessings of Liberty to ourselves and our Posterity, do ordain and establish this Constitution for the United States of America.”
It has no reason to talk of ideals such as ‘unalienable rights’ as we were no longer English colonies in revolt, we were now the People of The United States.
Like many new systems, it needed tweaking, thus the Bill of Rights..Amendments 1-10 were added soon after adoption of the Constitution and the establishment of our three branch government.
One should NEVER attempt to combine the purpose of two radically different documents