As I stated earlier, before the 1990s, practitioners in both Judo and Bjj viewed the hold that we now call Half Guard as a position of desperation that no one wanted to end up in. After Roberto Correa, Eddie Bravo, and Lucas Leites, the half guard is now viewed as a viable, and potentially devastating grappling position.
None of us even know how life was in feudal china.
Not saying you are wrong since yes, martial arts evolve. More now than before because today coming in contact with another martial art style is way less fatal meaning you can learn something and take it back with you home. Just saying you can't not know anything for sure.
TMAs evolve as well, all martial arts evolve. None look anything like it did 100+ years ago. Problem is that some want to think that the old style of martial art still exist in untouched shape and that it holds a magical key to kill all on sight if needed.
Does not mean old style martial art was not very effective in ways we can not imagine today, but terms were different. People died and often wore sharp weapons most likely.
In 50 years the techniques that today are so very important will no longer be of much concern, and new techniques that were today considered unused mostly will have evolved into something new and better. Once those techniques exist maybe these techniques will come back and once more evolve into the techniques they are today.
You forget that a technique when no longer practised regularly devolves to its most basic shape, once in that shape people will not focus as much on it and be less prepared for its application. This leads to new techniques evolving in ways that make it easier to bring back basic techniques and once again gain advantage. A circle of life.
Reason being, there are only so many ways a body may move, this will not change until we as humankind changes.