Black Greasy Substance inside my Copper Tubing, is it safe
Sounds like you have black sulfur. Unpleasant, but not especially unsafe. You could get a water test and know in more detail what you have in your water.

Anecdotally, I lived in a house that had a very bad case of that for a year or two, carrying in drinking/cooking water, and it was never an issue, though if I was away for a week or two the first flow of water from the pipes was solid black until it flushed itself out. I don't miss living in that house.