Yes. I agree. It is not about progress or sophistication, it is about success. And a little insect can be there a couple of millions of years while complex organisms are extincted.
But success is flawed in that most if not all species will eventually go extinct, but life won't. Life itself always seems to find a way.
I'd say success of individual species is subordinate to the grand scheme of things, of life finding it's way in what I would call progress. You could call it survival, but because species come and go, that's not entirely appropriate either.
This is a good example to explain that the free will is very limited. This person stops eating because of the current situation. Maybe he/she lost a loved person or became sick or became crazy to find a "meaning" in life but did not find one
The same person with a happy relationship, cute kids and strong health never would think about ending the own life.
It is not free will. It is just a result of a certain situation.
It's not a result of a certain situation at all, many people react differently to the same situations. That in itself should be enough proof of free will actually.
But you don't really seem to get my point of that comment. The ultimate proof of being in control of your life in the most literal sense possible is to decide whether you'd want it to end or not. Now I am not saying killing yourself is a smart thing, I very much believe in the contrary, but the fact that you could means you've got a free will.
Even an old dog stops eating if it wants to die.
Yep, the dog decides it doesn't want to live anymore even if it could still live for longer. Sounds to me even dogs have free will.

Old age is something inevitable yes, but not all dogs stop eating at exactly the same age. Some dogs never stop eating and want to life until the very last moment.