The delegates to the constitutional convention were, of course, all white men. About half had graduated from college. Most were investors or bankers of some sort whose financial interests lay with the value of stocks, or real estate. For most, the Constitutional Convention was not their first experience with government; most had experience serving in the Continental Congress or had served in Congress under the Articles of Confederation. Eighteen of the fifty-five delegates were in their twenties or thirties at the time of the convention, including such major figures as Alexander Hamilton (thirty years old) and James Madison (thirty-six). The average age was forty-two. I think it is fair to say that the delegates did not represent a "cross section" of the American public. Instead, they tended to be wealthy and educated; they were landowners, and, in some cases, slave owners -- in short, men with a stake in the economic and political stability of their new country.
The most distinctive feature of this group was its uniformity. The first thing to be noted is that the delegates were all white men. There were no women or blacks (although slave owners were well represented), and the Native Americans who were the original possessors of the land which became the United States were not included. Many of these men were middle aged or elderly, and came from prosperous backgrounds. Most were relatively wealthy and well educated. Thirty-five of the fifty-five men present had some legal training. Most were native to the 13 Colonies and had taken part in the Revolutionary War.
Many of the delegates were strong influenced by the ideals of the Enlightenment, and thus were more likely to be deists or more moderate in their religious beliefs than many other people of the period.