So true, the chemical arrangements/responses are caused by the laws of nature, which are laws of intelligent design too, as far as I think. This principle of nature being a response with many options, but following the paths of least resistance and probability, is overlooked by creationists who prefer a more contrived creation. But what you have pointed out is true, regardless of ID theory or not, and a very important factor in understanding nature. Although this places all life forms with a common ground, and I do recognise common ancestors, but as individual designs rather than a few common ancestors. I think in another post you showed that it has taken many common ancestors to produce a particular surviving type. It is a logical argument, but nature in our world does not seem to be so careful in selecting the best, and it too, is just stuggling to reproduce at any rate to survive.