Lord Kelvin is alleged to have said around 1900 "There is nothing new to be discovered in physics now. All that remains is more and more precise measurement." The few conundrums, the abscence of the ether, blackbody radiation, and a few other things, in facg brought about a complete revolution in physics. We know another revolution awaits us, when we can figure out how to probe the Planck scale. The lesson we must learn, is that while we can finish the work on current observations, we do nit finish the observations.
The tree problem offers a simple example. How do we define sound, as a causal property, or a subjective experience? Choose definition 1, yes. Definition 2, no.
Your other examples point to the bigger problem as seen in physics. The observatiins are not over. The definitions are dynamic, and affect future behaviour and observations. Choosing to isolate free will as a concept has consequences, and it arose out of theogeny and reconciling the problem of evil with idealisied monotheistic deity (not the biblical one, it should be noted). Philosophy is great at probing the assumptions we smuggle into our definitions.
Wittgenstein claimed to have 'solved philosophy' following this tack, as discussed on here:
Do mainstream philosophers believe that Wittgenstein "solved" philosophy? He more or less said, make good definitiins that follow clear consistent rules, and abandon the rest, "Whereof we cannot speak, thereof we must remain silent." His picture of philosophy was as a kind of therapy for our confusiin created around definitions. He continued to think and to write, but you might describe this as him taking his general theory and applying it to specifics. Most celebratedly, he dissolved the idea of Descartes that we are dissembodied thinkers, recognising instead that we do cannot have a meaningful private language. This dissolved many problems associated with substance dualism.
Ethics and decision making are essentially dynamic, we must constantly wield them against unknowable situations, and new behaviours and reactions of others. We cannot help but need and do philosophy, in doing that. Embryonic stem cells, artificial general intelligence, when to go to war in a nuclear armed world. There are no final answers, because the facts on the ground cntinue to shift, and new conundrums will emerge.
We don't solve physics. We reconcile apparently conflicting phenomena, or choose between models. Similarly with philosophy, we have results like Godel's Incompleteness Theorems which prove certain expectations are incompatible, or the private language argument which dissolves most of the ideas about a priori concepts. The real work of philosophy is to clarify definitions, so we can discuss experiences in the world meaningfully. Do not underestimate the value of that, only when it was applied to how to gain accurate knowledge of the world could science begin. But definitions are only the beginning, the real work is not in making sense of the past, but of the future.