Human remains have been found in Vasa, Mary Rose, a number of U-boats sunk in American waters, and the aforementioned remains from ships in Truk lagoon--most of these have been discovered inside the ships during salvage operations or by sports divers exploring wrecks. Bodies which settled on the bottom have largely disappeared due to scavengers and abrasive action of sometimes quite strong bottom currents. I suspect, if one were to explore inside the Titanic or the Bismarck, one would eventually come across remains. The Great Lakes, being very deep and very cold, with sluggish currents compared to the ocean, and being fresh water, appear to much kinder to artifacts and remains than the oceans.
Their shoulders held the sky suspended;
They stood and Earth's foundations stay;
What God abandoned these defended;
And saved the sum of things for pay.