According to its preamble, who is responsible for establishing the constitution?

The one who establishes the Constitution as per Preamble are the people. The first three words of the Preamble confirm that the government exists to serve its citizens. Since the ones who establish the Constitution are the people of a free nation, the Constitution then has the power to safeguard the interests of the majority rule and minority rights. All of these must be with the liberty and equality in mind. Along with these, all the states with the federal government must work hand in hand to achieve the nation’s objectives. Since it is the people who establish the Constitution, representatives must be wisely chosen so that all the concerns and rights will be properly taken care of. The sovereignty of all the citizens must also be always prioritized.