All may not be lost. I am leaning toward a loose cam chain that was left loose long enough to grind out some metal and then retightened to quiet it down. If the engine runs well, has good compression, and shifts through all the gears smoothly, I would flush it out and leave it alone. Watch it carefully for developing problems and try to find the cover that has the rtv on it and clean it off with a new gasket install. Most of that debris in the pan looks like rtv, small pieces of cam chain tensioners, carbon, and sludge. Of course if you are the curious type, or can't bring yourself to ride more than walking distance from your house because of this, tear her down.