Also, back then there was still a lot of disagreement about how the US would work. Was it going to operate be a single, unified country or would it be more like an EU style organization with a unified defense? IE Federalists vs Anti-Federalists? The electoral college was a compromise to let each state run its own elections and only franchise who they wanted. It’s important to remember that the US was not founded as a universal suffrage nation, and has only slowly and after much painful internal struggle expanded civil rights.

IIRC there was also a desire to put some distance between the unwashed masses and the election. James Madison, for example, was clear in his writings that he feared the system would devolve into mob rule by whichever group could whip up the most angry followers (January 6, 2021 anyone?). The presidential electors have an opportunity to be the adults in the room if the election is a hot mess and cooler heads need to prevail (though they can also swing the other way and wreak havoc so it's a double-edged sword).