There’s a couple different ways I could respond to this, but I’ll say this: the problem with your argument is that it’s basically a language game that doesn’t engage with nihilism itself. Even if I were to accept your argument, the language we use to construct nihilism’s premises might fall apart, but nihilism’s claim would not.
Even if the statement ‘as far as we know, human life has no meaning’ was proved to be categorically true and meaningful, this in itself is NOT a rebuttal of nihilism. It’s a reinforcement of its central point.
“The meaning of human existence is that it has no meaning” is not a solution or a rebuttal to nihilism. It’s just a fun language puzzle.
Also existential nihilism is a form of nihilism. It simply doesn’t have this paradox at all. Similarly, moral or ethical nihilism is not concerned with whether there is no universal truth - just with whether there are universal human values.
Guess what? Meaning is found/structured/created by language. Saying that it’s a language game doesn’t constitute a good response because your nihilistic philosophy is itself a language game. You can’t escape language.
The way I personally see it is that there is no universal meaning of life, but rather meaning itself is subjective. Like you said, for centuries the meaning of life was answered completely by religion for the vast majority of the world population. Even then, though, the answer was different from person to person depending on religious belief, but to each person it was the correct answer nonetheless. But as people begin falling out of religion, for better or for worse, the answer to that question for each person is being lost. So it is up to each person to create that concrete meaning, or for a new philosophy of life to be adopted by society that answers these questions.
But nihilism? You seem have a pretty firm grasp on it to the degree that you don’t let it weigh you down, just from seeing the way you post about it here, but the same can’t be said for most. To learn and accept that meaning doesn’t exist is depressing. Creating and strictly adhering to your own meaning is far more fulfilling than merely learning to cope with a meaningless world. And you can call it absurd, because we’ll all die and be forgotten anyways, but then there’s Marcus Aurelius, who found his meaning through philosophy and leadership and is one of the most celebrated leaders in history. Or Michelangelo, who found his meaning through art and whose works have become symbols of human achievement and culture. But even then, if you find meaning and an authentic goal and never become recognized, what does that matter? The meaning wasn’t for others, it was for overcoming challenges and feeling fulfilled with your achievements. So what if you’re forgotten a million years from now? So what if we all die? So what if people call you absurd? The question is how do we live our lives while being alive, and though admittedly I’ve surely read a lot less about nihilism than I assume you have, it doesn’t answer the question of how to live beyond merely coping with nothingness.
Yeah, you're totally right! You don't have to embrace nihilism to live a fulfilling life. But nihilism can creep up on you regardless of whether or not you want it to. Life can come out of nowhere and shatter whatever concrete meaning you're holding onto without a second thought. It also seems like you're assuming people will overcome life's challenges and find a meaning for themselves - but there's no guarantee that will happen. Furthermore, a nihilist wouldn't really differentiate between whether or not acknowledging life's meaninglessness is more 'depressing' or not, because it simply is the way things are.
I'll use Michelangelo as an example. He was extremely religious, and proved his devotion to his god through his works. Michelangelo would no doubt believe, and take comfort from, the fact that his name has endured through the centuries as a master of sculpture. Not only that, but people also still believe in sculpture as something that is beautiful and life-affirming, and people also still believe in the christian god. Our 21st century world affirms Michelangelo's existence, and his chosen meaning in life.
But for every Michelangelo, there's hundreds, maybe thousands, of contemporary sculptors whose careers never amounted to anything. Their statues weren't famous - they rusted away. Maybe they were fired from their guild and apprenticeships because they weren't good enough. What should those artists make of human existence? They probably sought refuge in their faith - but what should the 21st century human seek meaning in?
Money? What if you make a bad investment and it drains away, leaving you penniless? Family? There are all sorts of horrible things that can happen to people who try to find meaning in their family. Society? What about people born into broken states like Somalia, or girls born in ten years ago in Afghanistan who are about to be subjugated by the Taliban, or a Jewish kid born in Poland in 1930? Where's the meaning to be gained there? How can we find purpose in life, in a world where horrible things happen every day, and no one will tell us why?
Ever since the Soviet Union tested its first successful nuclear weapon in 1949, human civilization has had the capacity to completely and utterly wipe itself out in a single moment. Since then, instead of trying to avoid this future, we've actually gotten better at total nuclear warfare. We now have missiles that can streak across the world in 30 minutes. We have three thousand nuclear weapons, all of which are even stronger than the ones that leveled Horishima and Nagasaki. And for people in those two cities, who will give their lives meaning? Some people were simply vaporized by the bomb - instantly. They had no time to even acknowledge the fact that they were going to die.
The entirety of human civilization could just cease to exist in 30 minutes. And that's been the case for eighty years. This status quo only happened after many of the most famous nihilists published their works, meaning human existence has gotten even closer to the void since then. Is it willful ignorance and completely pointless to simply try to find a 'personal' meaning in life, knowing that the world doesn't care and could crush your personal meaning in life without a second thought? Nihilists would argue it is. Others, like you, would say it isn't.
(Also, I'm not trying to depress you or anything. I'm not personally a nihilist. I also really love Marcus Aurelius and stoicism, he's the f***ing man).
Guess what? Meaning is found/structured/created by language. Saying that it’s a language game doesn’t constitute a good response because your nihilistic philosophy is itself a language game. You can’t escape language.
Why does nihilism want to escape language? The fact that language creates meaning does not mean that this type of meaning is an objective moral truth. It does not answer the question "Is there a meaning to human existence?" It is simply a universal truth via a categorical statement - "All language creates meaning".
There are crazy ass versions of nihilism like ontological nihilism, which don't believe in reality as a concept and would take your language claims head-on, but I'm not going to argue from those because I don't really know them very well.