Woodward obviously isn't making every decision, but he does have the final say on all the big decisions. And for one reason or another, the large majority of them have ended up going wrong. Whether that's him himself consistently making the wrong decisions, the people he puts in place consistently making the wrong decisions, or the people he listens to for advice giving him the wrong advice, the end result is the same.
We need the person who has overall control of the footballing side of things to do a hell of a better job. Both in his own decisions and putting a better team of people around him. That, along with the fact that he's done the job extremely well at other admittedly lower level clubs, is why Rangnick would be my absolute preferred choice. From everything I've heard there's no chance he comes in unless he gets full control, whereas some others would come in and more work within the current system which obviously is not working (from what I've read of Henrique he seems more likely to do that).
Obviously Woodward would still technically be in charge, but ultimately the only thing he should really be involved in on the footballing side of things is telling the DoF how much he has to spend. Also if the DoF really isn't working out then it'd be on Woodward to replace him. Nobody is a sure thing and that option needs to be there, but obviously somebody with significant experience in that role would have a much higher chance of success than Woodward himself. Other than that, Woody should be focusing purely on the financial side of things (even though I don't think he's doing a very good job there either).