Any person in power might violate the rules and just because they happened to be one of the people who helped write them doesn't mean they wouldn't violate them. In fact, they would be more likely to get away with bending the rules due to being one of the people who made the rules.

That’s possibly true, but it’s usually not a helpful argument. The historical analysis typically is used to define the exception to a clear textual rule.

Here, the first sentence of Article II says: “The executive Power shall be vested in a President of the United States of America.”

You can say this isn’t a categorical dictate and there’s exceptions. One way to support that is by saying the founders created an independent central bank immediately, so they thought it wasn’t covered by this rule. But as you recognize, the founders could have just been breaking the rule. But that leads you to the conclusion that the central bank isn’t permissible.

> But that leads you to the conclusion that the central bank isn’t permissible.

The court could have just as easily have cited Framers that opposed the creation of the Bank as evidence the Constitution did not permit it. Or cited Jackson's strong opposition to the Bank as an example of there being a tradition of the executive taking control of monetary policy. My point is that the historical argument is arbitrary; you can pick and choose which examples get to be considered part of the canonical tradition to support preconceived conclusions (e.g. "the President shouldn't be allowed to interfere with an independent agency (the Fed)" or "the President should be allowed to interfere with an independent agency (the FTC)").