There was no such thing as a single national market at the time the Constitution was written and ratified. The vast majority of products were consumed locally; the few manufactured goods that existed were typically imported from Europe.
How different it was from today! How many local products do you consume on a daily basis? Practically none.
The creation of the single national market was largely a product of technological change, of course, but while it seems obvious and inevitable today, it was not. Without John Marshall and his expansive view of the federal power to regulate commerce, it might never have happened; railroads, for example, could have run into dead ends at state lines. At the very least, the development of our country would have been significantly slowed.
For that reason, you can easily make the argument that Marshall has as much claim to be the godfather of American capitalism as Hamilton. That is the case which is implicitly made in an exhibit at the National Constitution Center, and it has merit.