Not that anyone particularly cares about original meaning, but think folks should still say it out loud: For all of the things that are unclear in the founding documents and unknowabilities of what the Founders intended, "the President can kill anyone or commit a coup" was *never* legally arguable
I doubt the founders every really considered a Congress elected by the people would tolerate a President's abuse of power to such an extreme extent. They certainly didn't give the courts power to do anything.
It was essentially a check on the House of Reps, whose power balance was mostly determined by state populations. The House was the People, the popular majority. The Senate were the States.
Senators were also originally appointed by state legislators, not by the people, until state legislators were essentially bribed to appoint favorable parties to various interests.
Stop me if this all seems familiar to the situation we now have with the Supreme Court
Seem to remember (but don't recall enough detail to search it) senators independently engaging in foreign policy and treaty-making, and otherwise dabbling in what would today be firmly executive activities.
For a large part of the 19th century before the Civil War, the Senate largely overshadowed the Presidency. The Senate ran the county as the executive branch did not have nearly the power it had today
