This whole thing is looking to me like they assembled the engine with engine oil, (not the thick assembly lube like STP).
Then they forgot to prime the engine oil system before first firing it up.
Looks like inadequate oil supply by the looks of those bearings, especially that cam bearing.
Looks like the bearing material is just staring to transfer to the crank journals, another sign of inadequate oiling.
Crank will clean up fine and will remove any of that transfer material with a polish.
Lucky the bearings are soft and they take the first hit.
