What, precisely, are the missions of the Shuttle and ISS?

The Shuttle was sold as a low cost space truck, capable of carrying large payloads cheaply into space with missions as often as every two weeks. None of those things proved true except for the large payload and even that was less than promised. Add to that the deaths of two crews and the Shuttle comes off as a high priced lemon. As the Russians (and the US) proved over decades of experience, you don't need a crew to launch payloads, and the Shuttle is way oversized just to launch crews.

Dating back to the 1970s, I saw where NASA let contracts year after year for studies to justify building a space station. When Reagan announced the Freedom space station, the estimated price was $8-12 billion. NASA spent almost that much just doing design studies. They still have not found a good use for the ISS, especially with the reduced crew. If all you want is a place for two people to live, perform maintenance, and do a minimal amount of actual research while pumping billions to NASA employees and the aerospace industry, then I suppose you could call the ISS a success. If you figure in the price of building and operating the ISS, then it becomes a massive bureaucratic boondoggle.