I like to think that I know something about life. I've had 36 years of it. In that time, I've experienced much, and have met a diverse group of people, all of whom are driven by different things. Career, family, religion are some common examples, but there are so many others. If the world has taught me anything, it's that people have a broad and deep list of passions that drive them.
So what's the common thread here? Is there an objective way to say that something, definitively, is the meaning of life?
Yes.
The meaning is....
Life.
The meaning of life is life. That's the best answer I can give to a question that has no explicit answer. That answer may be seem like a cop-out, a profound insight, or, more likely, if you've previously thought about it, something that you've always known. The only purpose, or meaning, of life is to perpetuate, life. That's it.
Let's look at this through 3 different perspectives, the physical, the mental, & spiritual.
Physical
This is most evident in physical form. Life is a chain of complex biological processes that have figured out how recreate itself. We have even performed it in a lab, or at least the starting seeds of life (I leave it to the reader to frame what it means for their religion). Growing from that seed, we have the amazing tree of life. It's easy to be bewildered by its complexity and think what else it could mean, or where it's going.
Each tree branch is a niche that each species has found to self-recreate within Earth's ecosystem. Even when pressure is put on an organism, threatening survival, eventually evolution finds some way out. We see this all around us in many forms from the tiny to the large. Life is a continuation of this biological process, despite conditions changing around it. Many people think of evolution is some sort biological process that is constantly chiseling to perfection. I'd argue it's a path of least resistance that organism has found, to balance its needs to survive with what its environment provides.
This is the flow of life. It was put into motion long before we were here, and will be here long after us. Just like with the other mechanics of the universe, this is a force that makes life happen. Yet, no one asks about the meaning of Gravity; it's just accepted as a force of the Universe we live in. Likewise, the biological forces that make life happen in this cozy part of the Universe, is its own force, pushing us along with its own momentum.
Mental
Our minds, unarguably, have made us the apex predator of our environment. We've even named ourselves based on that trait, Homo sapiens, wise man. It has enabled our species to understand its environment to a greater degree than any other animal. It has made us understand and master, tools and communication, which has enabled us to work, in tandem, to form our modern global civilization.
And yet, despite reaching crazy levels of material prosperity, we still push our thoughts ahead. After solving one question, we follow it up with another, why? What next? Where are we going? It's questions like these, propelling the mind forward to new endeavors, that pushes the body forwards.
In physics, it's pushed us to create ridiculous huge devices for replicating forces that, according to the models of physics, have brought the universe into the state it's now. We've layered explanations of universe into complex set of theories that we're trying patch into one unified quilt that covers everything.
The academic world of physics is just one example of how our thoughts are an extension of life perpetuating itself. Thoughts or ideas survive based on its fitness (ability to explain the world), its ability to reproduce (transmit to another person), and how it competes/adapts with its environment (explaining or cooperating with other like ideas out there). And just like with the tree of life, there is a tree of educational disciplines forking off of one-another.
To use another example in more creative/abstract human endeavors. Take a look this great video essay called Everything is a Remix.
The elements of creativity Ferguson mentions in his video (copy, transform, and combine) are very similar to same forces for the continuity of life: reproduction (copy), adaptation (transform), and competition/cooperation (combine).
To use one last example, think of lodestar of our civilization: politics.
We've devised a complex framework of rules to codify our ethics of behavior. This framework of ideas gives us a theory of how we should conduct ourselves and what our hierarchy of values should be. Political philosphy survive based on reproduction (people adhering to its philosphy), adaptability (ability to change to the realities of people's needs), and competition/cooperation (to fight/ally in elections, or war in the extreme). They are self-reproducing systems of order based on the desire for order.
All these examples can be thought of life perpetuating itself higher up the Maslowian pyramid. Once survival, at a biological level, is stable we have other needs (e.g. to understand our world, to be entertained, to have a stable society) to fulfill. Each of these needs has its own competitive dynamic environment where it's seeking to find an equilibrium: a perfect understanding of the mechanics of the universe, a expression of creativity that makes us genuinely feel the spectrum of human emotions, or the best way for people to behave to achieve maximum harmony.
(pro tip: read about the Nirvana fallacy and understand that any political system / policy / etc. is ultimately a bunch of tradeoffs to an inherently intractable problem).
Spiritual
Harmony sounds like a nice way to segue into my last perspective, spirituality.
This is the hardest to pin down because it's the most abstract. Life has so many facets and so many great things to love about it, it's easy to focus solely one of its many aspects: life for the sake of life (e.g. raising a family, chasing love for the sake of love), passions, projects, & plans for the sake of passions, projects, & plans (e.g. hobbies & goals). But somewhere, between all those moments of life, everyone has that existential itch; what does all this mean?
Trying to answer that question, at its core, is an attempt at finding greater meaning, or purpose, beyond what is here and now. The question, by its nature, will depend on what you value, or what you ascribe meaning to. As such, the question is a great synecdoche for life; it's an unending series of questions and answers that will change as time goes on. Ultimately, no one will have the same exact answer as you, because we don't have the exact same thoughts/feelings at the exact same moment in time. Rather, we just have a constellation of overlapping interests/likes/dislikes that pull & push us apart as we're travelling our path through life.
The best way to see this embodied is religion. It has, over the years it's existed with humanity, mixed in the study of morality, law, philosphy, and science. All in the attempt to explain the nature of life, the universe, and our role in it, with the implicit thought that if we know the all answers, we'll have the ultimate guide to our meaning/purpose.
Just like with the physical tree of life, religion has grown, evolved, and branched into different spiritual niches with the times. We can take 2 large branches, like the Abrahamic religions & Dharmic religions, and trace their route through history for example. It shouldn't be any surprise that some religions, being an artifact of physical life, embraces the meaning of life through procreation (be fruitful and multiply).
Ultimately, religion has the same evolutionary pressures as previously discussed: reproduction of new adherents (both in the sense of offspring & trying to pass on culture/beliefs/values), adaptation to environment (e.g. protestantism forking from Catholicism, Christianity embracing pagan traditions), & competitive pressures (e.g. holy wars, the various schisms in the Islamic world). Throughout the ages, religion has evolved to fit the desires of people beyond the body and the mind.
Someday, I'd love to take a special look at Nihilism & Atheism through this prism. There is a sort of critical thinking in the philosphy of Nihilism, or the "religion" of atheism, that lends itself to a sort of life-rejecting, black hole, gazing into the abyss sort-of-way.
Sine qua non
So to wrap up this unsolved problem (hurrah! solved!) in a shortened, less grandiose way, the meaning of life, for you, is whatever keeps you alive, whatever keeps you going, whatever you live for.
If I still haven't convinced you, I'll leave with one last passing thought. The question What is the meaning of life? is non-existent without life; in a world absent of conscious creatures carrying the capacity to question their core essence, there would be no questions, no thoughts, nor feelings to inspire such a philosophical question. The question is, itself, an ultimate byproduct of life and its processes trying to understand its own nature.