My current theory is that life is like a machine which adapts and evolves in order to survive as long as possible.
No, that's teleology! There's no "in order to" in natural selection. Life doesn't care about surviving. It just either does or does not survive. Mutations happen due to imperfections in the DNA's copying mechanism, and some of them make the organism fitter, and some make it less fit.
There are some who try to derive what life does from the laws of physics.
If life doesn't care about surviving why do all lifeforms try to survive? That seems to be the only function of the genetic code.
The law of physics determine what life has to work with in the environment. The physics of nature determine all that is possible. Life tends to reproduce (make copies of it's designs) itself and persist as long as it can.