Explain who "the people" were in the Declaration of Independence.

Actually the phrase appears in the Constitution; although
Jefferson does comment in the Declaration that the delegates are
acting.

in the
name, and by the authority of the good people of these
colonies

The Constitution
speaks of "the People of the United States." It constitutes a deliberate contrast with
the opening lines of the Articles of Confederation, which read, "the united States of
America in Congress assembled..... Whether the Constitution means the individual
citizens or the States themselves comprised of the people has been an issue of intense
debate. It is an issue that dogged Constitutional scholars for many years, particularly
prior to the Civil War. The argument was, did the Union consist of the individual states
who formed it? If so they could easily separate from that Union as the Southern states
attempted to do. Or was it a union of the people of the union? If so, individual states
had no right to secede. Abraham Lincoln's position from the beginning was that the Union
was of the people, and not the states, so the southern States never truly left the
Union--they couldn't. It was for this reason when Lincoln planned to reprovision the
garrison at Fort Sumter, he wrote not to the Presidency of the Confederacy, which he did
not recognize, but to the governor of the State of South
Carolina.

The safest and probably most accurate approach
would be to interpret the language of the Constitution in its plain and simplest
meaning: "the people of the United States," who acted through their chosen delegates.
Even the Tea Partiers can't argue with that.