But even so, it was interpreted to mean different things by different people. What's more, circumstances have arisen which could not possibly have been foreseen by those living at the time. For example, it's beyond comprehension that the people of the late 18th century could have intended for Congress to have the power to regulate the gas mileage or pollution emissions of automobiles, since at that time there were no automobiles in existence. Or, as has already been pointed out, that they could have intended Congress to fund an air force. But the general language entitling Congress to do that was provided: it can "regulate commerce among the several states," and it can "provide for the common defense." Hence mileage standards, and hence the Air Force.

What I believe is that the vague empowering language exists precisely because the framers (or at least Hamilton) knew that they could not foresee in detail exactly what the government would need to be able to do in the future as circumstances changed. So a certain amount of flexibility on the part of the government was needed, and there were two ways this need could have been met.

On the one hand, what the government was empowered to do could have been made explicit, narrow, and tailored only to the needs of the day, but the process of amending the Constitution made relatively quick and easy, so that changes could be made to meet emerging and unforeseen needs.

On the other hand, the government could have been broadly empowered, but restrained by explicit guarantees of rights, and the amendment process made relatively slow and difficult, so that the powers of the government could change as needs changed, but at the same time the basic checks and balances and guarantees of liberty would be preserved against popular whim.

Obviously, the framers chose the latter course.

No, it isn't. That principle arises out of a case precedent in Marbury v. Madison in 1803. There were a number of constitutional issues involved, but one of them was whether a conflict between an act of Congress and the Constitution should be decided in favor of the one or the other. The Constitution doesn't explicitly say. The Supremacy clause of Article VI states:

Chief Justice Marshall's opinion in the case held that because the Constitution is mentioned first, before the "Laws of the United States," it holds a superior position, but that is actually a bit of a logical stretch; the plain interpretation of this passage recognizes no possible disharmony between them. It only elevates federal law over state law, so that state law cannot be used to nullify federal law. Yet it is, as we know, perfectly possible for acts of Congress to conflict with the Constitution, and the Court had the choice between interpreting the clause that way and so affirming Constitutional supremacy, or interpreting to the contrary and seeing the Constitution itself nullified by acts of Congress, rendering the entire basis for the government null and void. As a practical matter, obviously they made the right decision, but it cannot be pretended that they were not "legislating from the bench" in doing so.

It's really not that "the meaning of the text is meant to be fluid and changing." It's that many passages of the Constitution are sufficiently broad and vague -- deliberately so, in my opinion, at least in some cases -- that they may be interpreted in a number of different ways, all logically justifiable but one perhaps better suited to particular needs.

Anyway, as I noted the power of judicial review was not explicitly provide in the Constitution, but implied in the power of the Supreme Court to review cases and to be the supreme judicial authority. If it said it had the power of judicial review, who was going to gainsay it? And yes, the precedent of Marbury could indeed be overturned by a subsequent decision, but don't hold your breath.