You're doing a lot of conflating again, so let me pull things apart. First, labor excess value being extracted is again not a function of currency. It's a function of capitalism. In a capitalist system, capital owners are permitted the ability to extract excess from laborers so that they can invest that excess into new ventures. It has nothing to do with value perception. What does have to do with labor perception is how much wealth laborers allow to be extracted from them, which is the whole reason bargaining power is so important in a capitalist system for the labor class.

On fiat currency, in principle it isn't a terrible idea. What makes the dollar volatile though is that it is a fiat controlled by a single state. The gold standard worked better for the dollar because the value of the dollar would always be in effect controlled by gold supply, but this is something that can be worked out without gold as to avoid gold hoarding. We have modern solutions like crypto that could create an artificial line for the dollar to ride on, but that brings us back to it being easier to just have the dollar represent the buying power of the american market. If you keep that a function of public fiscal policy, it isn't all that dangerous.

On the Fed, the planning and writing of the bill that established the Fed being a behind closed door meet with the hyper wealthy does not make the Fed a private enterprise. It makes it a public enterprise that was constructed by private interest. Welcome to the home of the free, much of our infrastructure was built by wealthy business owners lobbying congress. That doesnt mean that the Fed can't be reshaped by the American people, it can, but the American public seems to not like taking the effort it takes to consider a bill that would reshape the Fed. Private interest groups do it instead because there is no competition.