They used to teach Civics in school so students could better participate in the democratic process.
As such, students would learn the Founders created the Senate "as a saucer to the teacup of Congress" to temper waves of public sentiment which tend to fluctuate wildly. In short, cooler heads would prevail.
And prior to the 17th Amendment, state legislators would offer up 2 representatives from each state to be Senators who would represent each state's interests. Therefore, smaller states would have the same representation as larger states. This compromise quelled the fears of smaller states who worried about being overrun by sheer numbers. It also allowed farmers in Iowa to have an equal voice as bankers in New York, for example.
The Founders took these steps because they understood history. Great republics of the past had been brought down when pure, unrestrained democracy caused extreme shifts in the underpinnings of a society. In essence, these steps would act much like a governor on a motor, not too fast and not too slow. Some refer to these checks as Goldilocks measures, not too hot, not too cold.
I mention all this because the Electoral College is a hot topic this particular minute in history and the very same principles apply with the Electoral College as with nominating Senators. Although a bit quirky, the Electoral College was designed by the Founders to be a saucer to the teacup of the national popular vote.
If each state's Electors were tied to the national vote, smaller rural states would become irrelevant. Presidential campaigns would spend all of their time in large populous districts. And as it pertains to the real life situation of today, the large populations of Coasties would overrun the smaller populations of Flyover Country.
The Electoral College, therefore, allows each state to have a representative voice that tempers that of the national popular vote.