Antinatalism as a philosophy is illogical. Just because our lives have been defined by suffering doesn't mean that life itself is inherently defined by suffering.
According to modern neural science, the human mind is programmed for negative biases. It is believed that this allowed early man and modern man to focus on what can kill us and made us adapted to survive. It is also believed this same pattern is found in other animals. The known species that didn't have this mindset, for example the dodo bird, lost their survival instinct and went extinct because of it. So yes, life itself is inherently defined by suffering. I will grant it to you, you addressed this in your next line but you also made another mistake.
We may be kept alive by biologically hardwired "survival instinct" but 99% of people never actually want to die for any meaningfully prolonged period of time. Even if they are very depressed, they recognize that they're at least lucky to be alive.
There was a long period of time where there wasn't a recorded case of a suicidal person, but the same can be true about diabetes, obesity, cancer, and so much more. This just shows these are issues that emerged with time changing environments. I'd argue that being alive itself is no long lucky per se. If it was, we won't say a dead cancer patient who's being suffering for years is lucky because they're not in pain anymore.
Even throughout famine, plague, hardship, inequality, and more, cultures throughout history have universally seen life and survival as a positive. They have been proud of their children and grandchildren, not just because they may not have had access to safe sex, or because they needed children for agrarian purposes, but because they believed that their children made their world and community a better place, and because they wanted to do their part to guide the next generation. Obviously, this is not true for every individual, but i do believe its true for every culture, even if those cultures may have had different ways of framing or expressing that idea.
What you stated here may be true in the past, and to a lesser extent true to day in third world countries. But every passing day, people are realizing this is no longer true. I'm not arguing that life and survival is actually a negative, that would be foolish to say. But so it saying it's inherently positive either. It's a lot complicated and nuanced. Like I mentioned earlier with the hypothetical cancer patient. One point I have to make is that people are now seeing themselves as a collection of individuals and not parts of groups (families, clans, races, nations, ect). I'll touch more on this later, but for right now I'll say this. Contributing to the next generation doesn't always benefit the individual. In fact in many cases, it can actually hurt them. Like if a child were to cut ties with their parents after the parents scarified time, money, and effort into them and won't see any returns.
As for the whole "didn't consent to be born" mind game, I find it funny that the communities I see this talking point coming from are the same ones who will hammer in the idea that minors/children are incapable of consent. Through this exact logic, isn't it also "immoral" to resuscitate a non-suicidal person who is ODing on opiods? They aren't conscious. They can't consent one way or the other. They will never suffer again if you leave them be, and they are guaranteed to suffer if you bring them back from the brink of death (apparently narcan hurts like a bitch). Moralized antinatalism (as opposed to simple child free preference) always leads to "EFILism" as a logical conclusion.
It is possible for a non-suicidal person to not consent to being resuscitated, if they have a DNR (do not resuscitate) order. Several people have them on their wrist, as medical IDs. Reasons why a non-suicidal person would have a DNR order for various reasons. Maybe they have a health issue that will cause them more pain that it worth. Maybe they're gonna die anyway, and resuscitation would be a waste of time and effort. Or maybe they no longer wish to longer suffer after they ODed. Whatever the reason, this still falls under the question of consent. You don't just consent via verbal or legal agreement, you can also consent via conduct. You conduct that implies you consent to being resuscitated after ODing is just living in society. You consent by default, and you have to go out of your way to withdraw your consent via DNR order. You can give consent and you can withdraw it. You really can't consent to being born, but you can withdraw it. (This is the difference between animatism and promortalism)
Antinatalists also usually like to point to climate change as a reason for why humans are inherently descructive and evil. But this is totally unscientific and lets the billionaire class maintaining and profiting off of climate destruction off the hook. The idea that there's no way humanity can exist on a large scale without being defined by greed and destruction is a talking point of the greedy and destructive. Don't spread their propaganda for them.
I want to point to the Environmental Kuznets Curve, the hypothesis that states the wealthiest nations actually contribute the most improving environmental qualities. However I will concede it is been challenged, criticized, and is only a hypothesis not an accepted theory or law. However, this is doesn't change the fact that most pollutions are actually being done by third world and developing nations. And the more people their are, the more they will pollute the earth. As for the super rich profiling off climate destruction, oddly enough they're the only ones who should have children. Because it seems only the very rich can actually address climate change. I mean, come on the poor and working class can't do anything when they don't even make up half of the world's wealth (or 3/4th depending on who you ask). It's not fair to be born in those classes and inherit a problem you can't fix.
And lastly, antinatalist practices hurt progressive causes because it's an idea entirely popularized among those left-of-center, leading to the next generation of children to be raised largely by right-wing bigots while all of the antinatalists other bits of cultural values, like anti-racism, anti-queerphobia, anti-capitalism etc fall into obscurity as messages kids get from their highly opinionated aunt, some random TV show, or even an essentric teacher, as opposed to the foundational understanding of the world they recieve as young children from the people who raised them
So the future's problems don't effect progressives then. They children won't have to face the world's problems, only the conservatives' children. This relates back to what I said about people being a collections of individuals and not a part of communities. That mind set is being held more by progressives. Like I said before only the rich should have children, so they won't have to suffer poverty and excesses hardship. If poor conservatives have children, than their children will grow up to resent them, the world, the rich, and the conservative mindset. Especially if they're born people of color, queer, or disabled. They cant' blame the progressives or the antinatalist.
And yes, the next generation WILL come, with or without the help of anti-natalists. The only question is whether or not you will have a part in shaping it. Christians understand this. But for some reason, secular progressives often dont seem to. If humanity goes extinct, it wont be because anti-natalists decided to not have kids.
Even problems like what South Korea is facing (which will eventually likely spread to the rest of the globe) wont result in extinction of humanity. It'll merely wind up with bottlenecking of the human population, the extinction of countless endangered indigenous communities, a redistribution of resources and power, and eventually a societal collapse where the small generation of young people are able to simply abandon and escape from the larger generation of old people depending on them for care. Let's just hope the society they build after us is based on humanist values and not some crazy fascist religious shit.
No anti-natalist believe they can stop the next generation from coming. They can only reduce it size to reduce the suffering, and it's already shrinking. And it's shrinking because life it no longer worth living for most people. The issues and results of the future is not the problem of the animalists. And is less of a problem of the promortalism.
All in all, I think antinatalism is just sort of a cope done by young people (especially young queer people) still living with their parents, raised in a materialistic individualistic bigoted society that is suffering a collapse in birth rates because it can no longer maintain the lifestyle only made possible by post-industrial "infinite growth" philosophy, and realizing that they're not going to be able to live the lifestyle promised to them as children, even without the economic cost of children, and let alone with.
What you say is correct, but doesn't disprove antinatalism. Society is collapsing and can no longer provide the quality of life it once did. If anything it seems another recession or depression is coming and ruin everything more. So there's no reason to bring children into this time.