At that time, the education rate among American citizens were pretty low. This was the reason why the founding fathers did not fully trust the people to elect the president. They're afraid that the people wouldn't be able to make an educated decision to choose the person who has the right criteria to lead the country. This was why they established the electoral college.
The electoral college consisted of representatives and senates that the citizens vote to work in the government. These representatives and senates tend to work for the interest of their own perspective states. They're the one who cast a vote to elect the president instead of the citizens.
