Inspired by, certainly. The founders were not ignorant and were aware of precedent.

But calling it "almost copied word-for-word" is not justifiable. On a trivial basis, it's literally not word-for-word in any way. On a more serious basis, there are significant changes in the laws, and enshrining something in an Act which can be changed by future Parliaments is a lot different that enshrining something into a Constitution which is much harder to change.

In fairness, the United States is a breakaway region of Great Britain.

A copy of the Magna Carta was in the National Archives for a while, and John Locke was a notable influence on founders such as Jefferson. Nihil novi sub sole.