I think there's a viable alternative to especially the "purposeless" based outlook, with the introduction of a recent concept called "teleonomy", which is an atheistic/scientific way to describe nature in purpose driven language. (In fact, as seen on Wikipedia/teleonomy, Richard Dawkins; recently introduced the treatments “archeo” and “neo” purpose. See his video/speech "the purpose of purpose".)
Anyway, for example, using the laws of thermodynamics, we can try to objectively discover non-trivial goals that humans may undertake, as far as nature goes. (i.e. grand purposes for the human species, that reasonably transcend the desires of individual humans, while seeking to be objective, much like how Science tends to follow the evidence, aiming to describe what the cosmos actually is, rather than what people may want the cosmos to be.)
Note: One may reasonably grasp an understanding of the summaries below, without clicking on the associated wikipedia etc sources. One may however get an even more wholesome understanding, by toggling the links conveniently provided throughout the summaries.
- Hypothesis A - An atheist PhD psychologist named Michael Price, hypothesizes that future humans are probably supposed to replicate universes  : "Michael's variant of Cosmological Natural Selection I"
The original version of CNS I stems from a concept called Cosmological Natural Selection by
physicist Lee Smolin.
- Cosmological Natural Selection, posits that our universe likely stemmed from a process that like evolution or biological natural selection, spun many universes; where the best universe instances emerge from universes that possess excellent replication abilities/properties, through the utilization of blackholes. Intelligent life is said to be an accidental by-product of this replication process.
- Cosmological Natural Selection I (CNS I), additionally posits thatintelligent life is a viable factor for replicating universes.
- Michael Price’s variant of CNS I, additionally posits that intelligentlife is a likely core influence on the successful generation of replicating universes, where Michael surmises that humanintelligence is the most “improbably complex” outcome of the cosmos thus far. Michael ranks modern humans to be a step in the direction towards future human intelligence, that will be able to create non-arbitrary universes. Thereafter, Michael expresses that the scientific purpose of humans is reasonably, ultimately to replicate universes like ours.
- Hypothesis B - An atheist computer scientist named Jordan Bennett, hypothesizes that a grand human purpose is probably to create Artificial General Intelligence  : "Why the purpose of the human species is probably to create artificial general intelligence?"
- In understanding Jordan's hypothesis, one may imagine entropy as a currency in an economy.
- Agents/organisms that get work done (access to activities) in nature, must pay up some entropy, you don't do work or have access to activities, without paying up some entropy.
- Highly Intelligent things (like humans) reasonably pay more entropy, compared to less intelligent things or non intelligent things, because humans do more work i.e. many cognitive tasks (thinking about science, doing scientific stuff) compared to lesser intelligences or non intelligent things.
- In a similar way, chimps may pay more entropy than say less intelligent things, because they do more work, or have access to more complicated activities. (More access to activities result from more access to stuff called "macrostates" in the OP's quora url)
- Likewise, Artificial General Intelligence [AGI] or Artificial Super Intelligence [ASI] when built, will have access to more cognitive activities, and they'll get more work done than humans. So, they'll reasonably pay more entropy to the thermodynamic system that is nature.
- This means there is reasonably a pattern, nature is finding more and more ways to extract more and more entropy from activities done (i.e. entropy maximization), and nature reasonably does this by building smarter and smarter things. Humans thus likely won't be the last thing nature finds to derive entropy from work; there will likely be AGI or ASI or whatever smarter thing that follows humans. (Laws of physics permits smarter things than humans overall)
Crucially, Science can reasonably describe how organic life began (namely, via evolutionary principle etc) and also, reasonably where human life perhaps seeks to go (again, via evolutionary principle etc, as described in the hypotheses above.)
- An atheist PhD psychologist hypothesizes that future humans are probably supposed to replicate universes  : "Cosmological Natural Selection, Cosmological Evolution and the Future of Life"
- An atheist computer scientist hypothesizes that a grand human purpose is probably to create Artificial General Intelligence  : "Why the purpose of the human species is probably to create artificial general intelligence?"
- Video summary: