How deep has man ever been into the crust of the Earth?
Well there have been a couple of threads that have talked about the deepest hole but it sounds like you’re talking about the deepest point a human being has been.
Check out this link to a geophysicist answering questions He seems a little unsure and this was from 1996 so it may be out of date.
"Q: What is the deepest mine in the world?
A: The deepest mine in the United States is probably the Homestake gold mine in South Dakota. People have been mining gold at Homestake since 1877. The underground workings reach to about 8,500 feet below the surface. The deepest mine in the World is probably the Western Deeps Gold mine near Carletonville in South Africa. This mine reaches to almost 4 kilometers (more than 13,000 ft) below the surface! Because the interior of the earth is still very hot, the temperature in deep mines can be very high, some times more than 140 degrees Fahrenheit. This makes working in these mines very difficult and dangerous. Cold, fresh air needs to be pumped from the surface deep into the mine to allow the miners to work. Sometimes, it is so hot that cold water must be sprayed on the miners to allow them to work. The high pressure caused by the weight of the overlying rocks sometimes causes the rocks to shatter explosively in what are known as rock bursts. Because of this, underground mining can be one of the most dangerous jobs and experienced miners are paid well.
The deepest holes on earth were drilled on land. Two holes in Kruna, Sweden reached 6.5 and 6.7 km depths, and were done for research purposes, like studies of geothermal gradient and crustal structure. Holes drilled for the purpose of hydrocarbon exploration in Louisiana reached depths of about 9 km, and in Andarko Basin, Oklahoma, about 12 km. There is another hole drilled to about this same depths on the Kola Peninsula, Russia, purely for research purposes. Because of extemely high temperatures encountered at that depths and related mechanical problems with the drill, progress became very slow and the Russians finally gave up."