Exactly. Self sufficiency is definitely a myth. Humans cannot survive alone for long. You simply cannot make tools that will keep you alive for long. You’ll have to venture back to civilization to get anything worked via metal at the very least. Just the basic crafts for clothing, shelter, tools and food is more than any one person can handle. It took whole tribes and villages even at the earliest points.

Now if you mean: how can I live in a cabin off the grid with minimal contact (1-2x a year) then that’s doable.