From a knowledge of the letters and how they are used and combined, we make words. From just the 26 letters in the English language more than half a million words can be formed. Words become obsolete. New words are constantly being made. But, the underlying letters do not change.
Fighting is equally dynamic and alive.
It changes with every generation. Techniques become obsolete. New techniques are constantly being developed. The underlying movements, on the other hand, rarely change. Raise your right arm.