My secular bent is about to be exposed for all to see, so if I happen to put something down that someone else disagrees with, please remember that all we're doing is sharing our thoughts about Shos's topic.
From an evolutionary standpoint, the "meaning" of life is to make more life. I haven't seen any life forms yet that don't do that. Individual organisms may not, but the choice is simple. Either enough organisms reproduce to propogate the species, or it goes extinct.
You ask: "Can even non-biological (as we know or don't know them) forms that change over time be said to have life?" Based on my statement, the answer is "no." That doesn't mean they don't have history and future, but it does mean that they don't propogate, at least as I understand the term.
You note: "Protagoras meant that nothing is absolutely good or bad.." I've done a little digging into what "good" and "bad" means, and although I'm far from an expert on the topic, I would like to share what I've found so far. Man, having evolved from "wild" animals, has a nature that causes us to want to take whatever we might feel the need for. When an animal is hungry, it wants to eat, so it takes whatever steps are necessary to that end, including killing prey. When an animal is cold, or tired, or feeling whatever deficiency it may have at the moment, it takes steps to alleviate that deficiency. It has no particular sense of responsibility toward others, it's interested in its own survival. There are species that don't line up with this description, which is intentionally intended to illustrate a point.
Well, humans with large brains showed up, and eventually discovered that, through cooperation with other members of their pack, they could kill the bear before the bear killed them individually, and survive to reproduce, so the basic tenet of natural selection was fulfilled.
But this is a learned activity, not necessarily inherent in our natures. So we have this conflict - our innate greed, tempered by our learned understanding of shared responsibility. The only thing that seems to be universally condemned is victimizing a member of your group. Members of other groups are fair game, because they compete with your group for things like land and food and water.
So, what is "good" is really just what improves your group's welfare, and what's "bad" is what detracts from it. A group that does not have standards of behavior that benefit it will not survive, but one that does will prosper.
Many of my more brilliant ideas have come to me in the shower, because that's where my mind goes through the transfer from sleep (random thought patterns, sense is not a requirement) to awake (realization that some ideas just plain suck, while others have merit), so I don't think that's unusual.
I make the distinction between knowledge and belief as that between personal experience and other ways of obtaining information. I know elephants exist because I have seen them in zoos and circuses. I believe they live in the wild in Africa and Asia because I have read about it in works by people I tend to trust.
But you're really concerned about what life means, right? Well, my life means making myself and my family secure and healthy. Then it means making my friends happy with my acquaintance. Then, it very well could mean making myself comfortable with an evening of classical music, or maybe even some good ol' rock and roll, depending on my mood.
--I know what I like--