Noted your points but most it deal with the fringes of the core, i.e. re,
I had stated there is no absolute meaning in the teleological sense, like one that is bestow and commanded by a God.
But within all available empirical evidence throughout evolution of all living things to the present, the core meaning of life is survival and procreation and maintenance of the next generation.
You listed many deviations from the above core purposes but they actually have no impact because nature has taken care of that and provided for assurances in terms of operating in large numbers. I stated the suicide rate is 0.034% for every 100,000 people, so the per annum is not critical in this case. Nature has taken care of the risk, even if say 50% decide to commit suicide we still have 3.5+ billion of ensure the preservation of the species. It is the same for the other deviations.
Yes, there were no species earlier, the essence is survival, self-preservation and extension to the next generation [including asexual reproduction] is inherent in living things.
Thus it is critical we understand survival and producing the next generation is the core meaning of life. In addition we need to understand what are the support systems within us that are critical to core. Then we must flow spontaneously with these critical elements.
Note FLOW;
en.wikipedia.org/wiki/Flow_(psychology
The other is peak experience:
Thus there are feedback, check and control points to guide whether one is flowing along with a meaningful holistic life.
Your counter as above,
since element/process X is part of the survival, then maximixing this input and process will maximize survival and meaningful life;
is a wrong view.
There is always an optimal level of input and a holistic approach.
Note Diminishing Marginal Returns from economics;
Like it or not, all humans are like a “servomechanism” and to be most effective one has no choice but to understand and adopt what the empirical-based meaningful purpose of life [with reasonable room for deviation] to avoid pains and to achieve flow, peak experiences and self-actualization.
As for a meteor that could appear suddenly in sight, fortunately due to the survival impulse, humans has progressed exponentially in knowledge and technology to the extent we have the potential to take care of meteors that come our way in the near future.
As for other threats not anticipated and beyond our means to tackle, we have to accept that possibility but at least we have try our very best driven by the impulse to survive at all costs which is the implicit purpose toward a meaningful life.
We have to apply philosophy-proper to abstract this reality and make it explicit to all humans.
Your OP’s theme and hypothesis is not recommendable for humanity. If that is really so, then we all might as well take poison now and end it all instead of going through a meaningless life that is full of sufferings.