But all this got me thinking that if there was a Daoist inspiration for martial arts it would be as a natural expression of what a human being is. In other words it would have been created because we are naturally inspired to fight. Natural inspiration itself would be the source of the art.
Daoism is about 'returning to the source.' While we don't know what the source "is," we can still trace our way back toward it. Exploring the development of the fetus is a great example of this. Anatomy aside, Daoist Internal Alchemy (neidan) has a practice called making a fetus inside. It is an exploration of the idea that the way each of us developed from a fetus is still inside us. We still have access to the original growth and movement patterns that we developed in our mother's womb. We have access to these original patterns when we return to "the source" in stillness.
Similarly we find a Daoist exploration of inner evolution. The idea is that we are capable of moving, perceiving, and even thinking, in all the ways each of the animals in our evolutionary history moved, perceived, and thought. I don't believe they had the idea of evolution as we know it today, but they had two simular ideas which got them deep into this exploration of "the source."
The first idea was that the fetus, once implanted becomes "shrimp-like" and then "a wind comes" and it becomes "fish-like" and then "another wind comes" and it becomes " reptile like" (you get the idea). The second idea was from shamanism, namely that we can invoke animal spirits to take over our bodies, becoming for the duration of the possession like the possessing animal spirit in movement, perception and mind. This idea was explored in Daoist circles as physicality (jing and qi) also arising from stillness, however without the spirit possession component.
Daoism can indeed be a major source for the development of martial arts but any stories about the need to fight being a Daoist source of martial development are highly unlikely. Fighting skill is a natural form of human expression like singing and dancing, it did not develop out of necessity.