Yes, this is the way I am useing natural. Current enviromental conditioning is not natrual. The natural state of man is to hunt and gather. Those are the conditions we evolved under.
Chris, with all due respect there is no reason whatsoever to think humans naturally used something like the dantien articulation of the sort that you'll see among many good practitioners. That is an unusual and obviously deliberately learned skill.
In a more general sense, evolution dictates that natural movement is efficient. Our primitive ancestors could not afford to waste calories. If you need to grab something light with your hand, you naturally use local arm strength because that's the least energy demand to get the job done. That is not what the internal mechanics being discussed are about, in one sense they are about getting your whole body involved even if you only need to move your arm. It sacrifices calorie efficiency in order to allow more power to be expressed without losing it somewhere or exceeding the tolerance of part of the linkage. That's just one facet of their unnaturalness, but one is enough to torpedo the notion that this is natural movement by any definition of natural.
To use an off-the-wall example, most people have probably experienced something like this: you open the refrigerator, go to grab the milk, and it goes BWANG! as you hit the top of the fridge with it because it's nearly empty when you expected it to be full. Your brain judged how much arm power you would need to lift it, and before you could adjust you overshot it. Similarly if we imagine it were filled with lead as a joke, many people would practically fall over or at least become unbalanced from the unexpected load. That is the "natural" way of doing everyday things, the "external" way. That is not the way it would be done with internal mechanics. Now you can try to become really fast at sensing and adjusting how much force you apply in what direction so that you stop yourself from overcompensating, and this is what most people do as they develop skill. The internal approach is to move in such a way that your structure isn't going to become easily disrupted by the unexpected size or direction of a force, among other things. This gives the ability to react instantly and have power available instantly, rather than having to regain structure first, and then react, maybe overshoot again, have to regroup, etc. The martial utility of such skill should be rather obvious, and that's only one facet of it. In no way shape or form is it natural or anything that can be learned without *unlearning* what you do naturally, and trying to completely repattern movement.