In my eyes, the American Creed is an unspoken statement of all those who live in the United States that commits them to working towards a better for themselves and their country, whatever that may mean to them and whatever that may require from them. The underlying principle that drives this idea is that such a future is not defined, but one that is defined by those who seek to create it, and is only as concrete as the resolve of those constructing it. The institutions and machinery created under the Constitution are designed with this sole idea in mind, that regardless of context, those who involve themselves in it are those who define what it seeks to accomplish. But beyond this, every inch of this nation is designed in such a way that it aspires to this goal at every level, from the national government to the everyday family, so that the future of America will be defined by those who give it life.
This creed finds root in the everyday citizen, the observant individual who sees events in their community, their nation, and the world, and makes a clear decision on how to view this event that's based on the context in which they view it. This may be what school they go to, what their family is like, where they go to work, and so on and so forth. The decision they make from the stimulus they receive, influenced by how they receive it, is what will drive the action they take going forward, however small or large. Hearing of an event at their church may lead them to volunteer, seeing a march down the street may lead them to vote for a certain candidate in an upcoming election. It matters not what this decision is, but that everyone who makes such a decision will, undeniably, take actions that reflect this decision both in their lives and in the lives of others, no matter how small the influence may be.
A major symptom of this is hard work, not only as defined by a vague phrase used to describe success, but as a means to an end for those who wish to produce change. If someone forms an opinion of how the world should be in their eyes, they will not only take action to reflect this, but will work hard to make sure that this change takes place in a meaningful capacity. Looking at any point in American history, it is evident that this hard work is at the core of all landmark changes that redefine what the United States stands for, and considering that this creed is the future that we define, it's inevitable that part of this creed is built on the foundation of hard work.
Another part of this creed is that it takes the form of those who take it on, and seek to embody it within their own lives. It will only ever reflect the body of people that it will inevitably affect, and thus the future of America is defined by those with the capacity to make it happen. This means that those in office, those who elect them, and those who carry out their actions will define what future America finds itself in as it persists, which is the root of both the American Revolution, and every single revolution that has taken place in America since then.
Finally, the American Creed fundamentally maintains the goal of doing the best for those around you and those who will come after you. As a cliche quote, those who plant trees whose shade they will never enjoy are those who have taken on the American Creed. Having a vision that goes beyond what you will experience in your lifetime is the ultimate way to live through the strife and difficulty that you will encounter when trying to enact said vision. That, is what I believe the American Creed is.