Pieces of steel in cylinder??

Righty Tighty said
Originally I was going to reuse the cam, but since I have the motor completely apart, I’m going to replace just about everything. I’m still wondering what caused all this. Could it have been solely through overheating? Or is there another factor here?

Yes good idea to replace the cam, the lobes on the old cam were put under undue force when the valves bottomed out. They will likely chew out any new lifters you put on top of them, even though they look OK at a glance.