At the time it was proposed the concept of a Bill of Rights—not to mention the specifics of what would be in it—was controversial.
Some argued against the Constitution itself as defective due to lack of an enumeration of the rights of the People. Even as English colonists subject to the Crown they had enjoyed, or at least claimed, the traditional rights of Englishmen, including those set forth in the 1689 English Bill of Rights and earlier documents going back to Magna Carta of 1215. Surely as the free citizens of a republic they ought to enjoy such an enumeration of rights.
Others argued that the Constitution was intended to provide only for the arrangement of the national or central government of the States within the Union and that an enumeration of citizens’ rights was unnecessary as it was the People making the Constitution and, therefore the People retained all rights and powers not specifically granted the national government. Alexander Hamilton made this argument in Federalist No. 84.
The compromise, which was finally enacted, satisfied both by setting forth eight sets of specific rights of the people that the national government (and later, by incorporation under the 14th Amendment, the States) is bound to respect. Those amendments are followed by the Ninth clarifying that every American citizen has all the traditional rights of a free person whether or not specifically listed in amendments one through eight. Then the Tenth Amendments makes clear (although somehow not so clear to some of the Democrats and liberals in Washington today) that the national government has only those powers specifically granted by the People through the Constitution, with all other powers reserved to the States or to the People.