The creation of the position of the presidency is a move by the founding fathers inspired by a desire to create a strong central point in a newly established government. The worries of the founding fathers were based on their past, and concern for generations to come. They framed the constitution with multiple goals in mind. First, they wished to move away from the strong central power placed in a hereditary king by giving more ability to states and separating federal power between three branches. What also aided in the creation of the presidency is historical precedence. They looked to the Romans to learn what can work in a democracy, but also more importantly, what does not work. In my opinion fear of failure is what lead the framers to create a presidency in the way they did. After realizing what the failures were of past iterations of democracy and republics, they avoided them knowing what would happen if the second attempt at a federal agreement would fail. With failure comes the threat of the British coming back to retake the colonies after their slow implosion.
Presidential powers as explained in the book play a large role in both domestic and foreign matters making them vastly important which demands a strong leader. Without a central figure to direct the political traffic standstills are inevitable and trade dwindles. Creating separate branches helps to check powers, but it also frees up the president to make better use of his own. Using that power the president becomes the de facto spokesman for the United States, and hopefully, they portray the wishes of the people. This also becomes important in times of war as commander in chief the President can be a civilian counsel. The President has many roles to play and due to that he must fit certain criteria.
After realizing what may happen in the future and putting into words their plans the next step in securing the presidency for future generations is making sure it works in the first one. Had the first presidency been a failure significant pushback from the states was a strong possibility. George Washington as the first United States president was and remains to be a strong choice that not only affected people at the time but remains to have a large impact on the way the presidency is conducted today. His ability to create certainty against a tired and uneasy people propelled the presidency forward. Coupling that with his decision to retire early creating a moral standard for presidents allowed United States citizens to believe in what a presidency could be.
You have good points about political development but you need to answer the question specifically. Given what you note in paragraph one, how did the 1787 Convention start with the concept of an executive council (as proposed by both VA and NJ plans) and then end with a singular president? What makes this happen?