These states, that early in the game and having just won a war of independence without the help of central government

But they did have the help of a central government.

Copying from the website The Boston Tea Party

The First Continental Congress feared that a standing army could be used as an instrument of tyranny. This attitude changed after the Battle of Lexington and Concord. The Second Continental Congress approved the formation of the continental army on June 14, 1775. The legislation placed the militia forces, then fighting outside Boston, under federal control. These troops formed the nucleus of the army. The date is still celebrated as the birthday of the U.S. Army.
Its One and Only Commanding General
George Washington was named commander in chief on June 15, 1775. He assumed command of the army in a field in Cambridge, Massachusetts the following month. Washington served as commanding general for the entire war without a salary.

The 13 states did unite under one central government, the Continental Congress. They came together as a unified entity, a national government. The war could not have been won if each state fought separately. As it was, the fact that our newly formed army beat the British was a miracle.

After the war the individual states were loathe to give up their independence. They formed a loose association called the Articles of Confederation. This form of government, however, proved to be too weak to deal with the matters of a unified country--commerce, defense, etc. That's when the decision was made to draft a new form of government, under a Constitution. This government would have greater powers over the states and individuals. Each one of the states had to ratify the new Constitution. Each state had to approve all the provisions of the Constitution. The original document, ratified by all the states, had seven Articles and ten Amendments (the Bill of Rights). So...originally, all the states agreed to the Constitution in that form and their association with the government was voluntary.

The Constitution we have today is not that original document. That document has been amended over the years and interpreted. Obviously, there are a lot of issues :)))