"Primitive" denotes a low level of skill and/or a rudimentary technique. It also implies that no one else has ever done what you are trying to do. After all, "cave men" drew "primitive" figures on the walls of some caves; school children who do the same are called "beginners," because there are lots of artists these days.
And, as an aside, I'm not so sure about how "primitive" those cave artists were ... I have seen some modern Chinese work, it was a painting of a flock of birds, and all you could see was a landscape and a couple of strokes representing the body of a bird disappearing off the side of the picture. The painting was skillfully done and truly gave the impression that the birds were moving ... because they were already gone! Similarly, the cave artists reduced their work to just the essential lines that would look like a bounding deer, to someone who has seen a bounding deer.
OK, back to the question. "Ancient" denotes a distance in time, from where you are. "Ancient" could mean "older than a week" (describing bread), or "older than thirty" (describing a person, if you yourself are under twenty
), or "happened before I was born," or "happened a thousand years ago," or even a longer span.