The first thing we need to keep in mind is that people are not perfect and we know it. We are capable of learning and understanding how and why something "should" be. We, as imperfect people, lack the capacity to consistently live up to the expectations, ideals and standards that we identify.
That's just the reality of not being perfect. We WILL screw things up. Sometimes unintentionally, sometimes on purpose. Regardless, if it can be screwed up, humans will find a way to do so, sometimes spectacularly.
The founding fathers knew this. They counted on it. They took it to the bank. They knew they were imperfect and that all other people are as well. That's why they recognized God in the founding documents and attributed the natural rights of people as coming from God. No imperfect person is then in a position to nullify or deny those natural rights from God because, they are imperfect and thus cannot over-rule or countermand what God has put in place.
They also spelled out that the U.S. is a land of law. No person is above the law and the laws are (supposed to be) based on protecting those natural rights. The laws are written high up on the wall for everyone to see, so to speak.
The Declaration of Independence and Constitution are the ideals and expectations that citizens here should expect of each other and make every effort to live up to themselves. Will we fail in the effort to do so? Of course we will. However, what's important is that we continuously make the effort to do so.
That's why those rights and laws are taught so that we learn them and we are continuously reminded of them so that even if we fail at some point in our efforts to meet them, we know what we need to do to get back on track.
Did those imperfect people who set those rights, rules and expectations on paper live up to them themselves? No, they did not. Why? Because they were imperfect but as long as people kept learning and understanding them, then in the long run, as long as we keep making the effort, we we continue to get better at meeting those expectations.
This is why the people who think these documents are "living" and flexible are dead wrong. It is the intent that each individual makes the changes in themselves to meet the expectations, not change the ideals to accommodate imperfections.
Each of us is supposed to make the effort to meet those expectations and ideals of American liberty, freedom and accountability for every individual.
We keep trying our best to change ourselves to be the people we know those documents tell us we can be. It's up to each of us to make the effort all day, every day.