If you had a concrete, straightforward point to make, you'd have made it already.
I have made the point. In fact, several points about the erroneous presuppositions your original claim makes. If you want a one liner tl;dr, well, here it is: evolution does not contradict telos or the existence of human nature.
Now, explaining what your presuppositions are and why they are wrong (or as genteel academics like to say, "problematic") is a longer discussion, one that I tried to outline. Why do you expect that a simple explanation is always possible? It is true that you will need a certain measure of philosophical maturity to appreciate the arguments, but this is unavoidable.
It's really quite unclear how any of this has anything to do with the original question of what one should prioritize, or what your specific teleological answer to that question is.
My original answer isn't intended to tell you what the point of human life is. I could give an answer, but that wasn't the intent. The only point was to indicate that human nature, its telos, determines the inherent ends of an organism. In fact, the nature of an organism is ultimately a matter of telos. Its form and matter, anatomy and physiology, are downstream from telos.
From what I understand, it seems like you're saying that the concept of human nature cannot change, because it's inherent in the definition of a thing's nature that it doesn't change.
By analogy, if the nature of triangles is triangularity, i.e., to be a geometric figure with three sides, then what it means to be a triangle is fixed. Now, if you take a triangle and start hammering at it to give it a fourth side, then you've changed the given triangle into a quadrilateral, but you haven't changed triangularity. It's just that triangularity is a predicate that doesn't apply to your quadrilateral, because you have something else now, a quadrilateral. But if, instead, your triangle is red and you paint it green, then it is still a triangle, but it has changed. It simply hasn't changed in any essential manner.
Human beings can adapt in the latter manner. We can develop darker skin in sunnier climates, lighter eyes where pigment isn't needed, sickle cells where malaria is rampant, or whatever. Still human. And I maintain that this has been true for a long time (I would make a stronger claim here, but it is not necessary for the present discussion). If, however, some change analogous to the triangle-to-quadrilateral transition were to occur, then we simply have a new species. Humans haven't changed in this sense, that would be absurd, as such a change is a negation of human nature. Instead, we just have some new, post-human species. That doesn't undermine the notion of telos. It just means that maybe the essential telos is different for these post-humans. It would have to be, or else they wouldn't be a different species.
I just clicked on the books you mentioned, and it seems to me that 1) there is some deeper argument at work here, and 2) you are just repeating the argument from the book, or at least not explaining its argument in a more coherent form amenable to a HN discussion.
I wasn't actually using arguments directly from those books. I don't recall, for example, what the first book says, as I haven't touched it in over a decade. I only mention those books as resources for those who wish to better grasp some of what I've said. I hope you find them informative and enlightening.
As for your questions...
1. The organism which comprises the thing we call "human" has changed, over time, and will continue to change. This seems...scientifically uncontroversial to me.
See above. If you continue to classify your quadrilateral as a "triangle", then that is a failure to account for the substantial change in your language, hence the confusion. This is what I meant when I spoke of the errors of nominalism.
2. And therefore, my argument is that trying to derive some sort of ultimate teleological purpose from this clearly changing thing is fruitless, and one's effort is better used toward accepting change.
Also see above. A change can be accidental (like refinishing your triangle with green paint) or substantial (like hammering the triangle into a quadrilateral). The first preserves the essential identity of the kind of thing it is, the second changes the nature of the thing. So it's not fruitless. Different species will each have a different telos.
3. Additionally, this way of talking about telos is also quite embedded in a worldview that was pre-evolutionary, which IMO makes it suspect from the start.
That's your hangup, but it is an uninteresting one that poses no threat to telos. Science and the very viability of science rests on many philosophical presuppositions that predate whatever scientific developments have occurred since, and that includes telos. And in fact, any ostensibly "scientific" claim that contradicts those presuppositions cannot be admissible even in principle, as it could not be scientific by definition, as it would refute the very methods of scientific justification that the claim is supposed to rely on. Indeed, it becomes a philosophical claim and must enter the ring of philosophical debate.
Comments
I have made the point. In fact, several points about the erroneous presuppositions your original claim makes. If you want a one liner tl;dr, well, here it is: evolution does not contradict telos or the existence of human nature.
Now, explaining what your presuppositions are and why they are wrong (or as genteel academics like to say, "problematic") is a longer discussion, one that I tried to outline. Why do you expect that a simple explanation is always possible? It is true that you will need a certain measure of philosophical maturity to appreciate the arguments, but this is unavoidable.
My original answer isn't intended to tell you what the point of human life is. I could give an answer, but that wasn't the intent. The only point was to indicate that human nature, its telos, determines the inherent ends of an organism. In fact, the nature of an organism is ultimately a matter of telos. Its form and matter, anatomy and physiology, are downstream from telos.
By analogy, if the nature of triangles is triangularity, i.e., to be a geometric figure with three sides, then what it means to be a triangle is fixed. Now, if you take a triangle and start hammering at it to give it a fourth side, then you've changed the given triangle into a quadrilateral, but you haven't changed triangularity. It's just that triangularity is a predicate that doesn't apply to your quadrilateral, because you have something else now, a quadrilateral. But if, instead, your triangle is red and you paint it green, then it is still a triangle, but it has changed. It simply hasn't changed in any essential manner.
Human beings can adapt in the latter manner. We can develop darker skin in sunnier climates, lighter eyes where pigment isn't needed, sickle cells where malaria is rampant, or whatever. Still human. And I maintain that this has been true for a long time (I would make a stronger claim here, but it is not necessary for the present discussion). If, however, some change analogous to the triangle-to-quadrilateral transition were to occur, then we simply have a new species. Humans haven't changed in this sense, that would be absurd, as such a change is a negation of human nature. Instead, we just have some new, post-human species. That doesn't undermine the notion of telos. It just means that maybe the essential telos is different for these post-humans. It would have to be, or else they wouldn't be a different species.
I wasn't actually using arguments directly from those books. I don't recall, for example, what the first book says, as I haven't touched it in over a decade. I only mention those books as resources for those who wish to better grasp some of what I've said. I hope you find them informative and enlightening.
As for your questions...
See above. If you continue to classify your quadrilateral as a "triangle", then that is a failure to account for the substantial change in your language, hence the confusion. This is what I meant when I spoke of the errors of nominalism.
Also see above. A change can be accidental (like refinishing your triangle with green paint) or substantial (like hammering the triangle into a quadrilateral). The first preserves the essential identity of the kind of thing it is, the second changes the nature of the thing. So it's not fruitless. Different species will each have a different telos.
That's your hangup, but it is an uninteresting one that poses no threat to telos. Science and the very viability of science rests on many philosophical presuppositions that predate whatever scientific developments have occurred since, and that includes telos. And in fact, any ostensibly "scientific" claim that contradicts those presuppositions cannot be admissible even in principle, as it could not be scientific by definition, as it would refute the very methods of scientific justification that the claim is supposed to rely on. Indeed, it becomes a philosophical claim and must enter the ring of philosophical debate.