There were many different interests and views on government represented at the Constitutional Convention, and the document that emerged to a large extent reflected a series of compromises between these. Let us look at a few of these.
One key divide was between the delegates from states with large populations and those with smaller populations. This divide emerged as a key conflict at the convention when James Madison's so-called "Virginia Plan" called for a two-house legislature in which each state's representation would be determined by its population. This clearly favored larger states (like Virginia). An alternate plan, known as the New Jersey Plan, included a unicameral legislature where each state, regardless of population, would have a single vote. The compromise that emerged from this debate, sometimes known as the "Great Compromise," included elements of both plans. It featured a House of Representatives where representation was based on population and a Senate where each state received two representatives.
Another divide in the convention was between states with large slave populations and those without. This question also revolved around the issue of representation. Southern states wanted their enslaved populations to count for population when determining representation, and Northern states did not. (Incidentally, the two groups took opposite positions when it came to determining population for a direct tax that Congress could impose on the states). This question was resolved by the so-called "Three-Fifths" compromise, which counted that percentage of the enslaved population for each state to determine its representation in Congress.
Other compromises included the stipulation that Congress could not tax exports as well as a stipulation that the slave trade would remain untouched for twenty years after the establishment of the Constitution. In fact, almost every aspect of the document reflects some sort of compromise. The principle of federalism, which divides powers between states and the federal government, was a compromise between those who sought a powerful centralized state and those who wished to retain the essential relationship between states and the national government that existed under the Articles of Confederation. The election of senators by state legislatures reconciled the views of those who wanted a more democratic government and those who wanted senators to be appointed by others. The electoral college represented a similar compromise. Ultimately, the Constitution was a political document, hashed out between politicians with a variety of different interests, and the "horse-trading" that characterizes the political process, as much as high-minded political theory, helped shape it and the American government it established.