Trump didn’t pick Jackson because of his depth of management experience in big organizations. (Jackson doesn’t have that.) He didn’t pick him after a long and deliberative process that included consultation with Republicans (and Democrats) on Capitol Hill. He didn’t vet Jackson fully to ensure that he could even be confirmed. (Jackson was tapped as the top White House physician by President Barack Obama in 2013; that position does not require Senate confirmation.)
Trump picked Jackson because he liked him. Because he thought Jackson did a good job at that news conference announcing the results of Trump’s physical. Because it felt like the right move.
All of that means that where the White House finds itself today with Jackson — dead in the water unless something changes — was entirely predictable. Governing by the seat of your pants is rarely a recipe for success; there’s a reason, after all, that things like vetting exist.