And, once again, you are removing a step. You don't work so you can have sex. You work so you can pay bills. You pay bills so you can have shelter. You seek shelter so you can keep yourself alive long enough to have sex, and then in turn keep your children alive.
Except you can totally and very easily remove the sex portion of this from people's lives? Like... From people that are fine living the rest of their lives single, from asexual people, from widows that don't want to re-marry...
Not to mention that the "sex -> keeping children alive" leap has no logic. It's part of a completely separate logical sequence of "seek shelter -> keep yourself alive -> grab resources to keep your children alive", which yes, has similar steps, but has no correlation with sex at all, except for the fact that you "need" sex if you wish to have biological children... Unless you live in modern day era and can use artificial insemination... Or if you just don't want biological children and are fine with adoption, for that matter.
Yes, it sounds ridiculous if you remove those intermediary steps. But, if you omit sex from the equation, then your evolutionary line ends. Literally everything does actually relate back to sex.
Except many people don't care? You don't need to think about evolutionary line to live your life.
Sure, you can argue on subconscious bias or whatever because of evolution, but... Not everyone needs children to be happy, and not everyone who wants children needs biological children, and not everyone needs sex regardless of them wanting children or not.
Like, hello? Homosexuality has been a strong part of humanity for as long as humanity has been a thing, and homosexual couples being able to have children is something very very recent... If the only reason people "need" sex is for the progress of humanity like you said, then the argument is flawed by default because homosexual couples have been fine with not progressing humanity since forever.
And again, asexual people exist, and sexless marriages exist too. People's lives don't revolve around sex, geez.
(BTW: Your logic on the everything is to drink water counter-example is flawed, because drinking water is part of keeping yourself alive. And, once again, anything and everything that's done in order to keep yourself alive is based on living long enough to later have sex. Humans, as a K-type species, also live long enough to in-turn raise their children and then grandchildren afterward, which is why we live as long as we do.)
Okay, let's go with this line of thought.
Theory: Everything we do is related to sex.
What do we need to have sex? Stay alive.
Therefore, everything we do is related to staying alive.
With this in mind, the only way to become a good writer, is by writing survival-focused stories where the MC is thrown into an island or whatever and needs to struggle to stay alive, as that is the core of humanity and all our lives revolve around that. As we can't have sex if we're dead, so we need to write about the struggles of survival if we want to become good enough writers to become capable of writing about sex, so that we can write about life.
... Yeah, that's stupid. It's absolutely stupid, but it's using the same line of thought you are using.
If you are not looking at things from the perspective of evolution, then you are looking at things through a very flawed lens that does not reflect reality. Evolution is a hard science that literally governs everything in our culture and society. There is no arguing your way out of this point, unless you want to go the full creationist route.
Evolution is a small part of what makes people human. Culture and Society has a much bigger weight on everything we do than evolution does. And no, they are not governed by evolution.
Like, Evolution is not what decided that "Boys wear blue and girls wear pink", that was society.
Evolution also didn't decide that "homosexuality is a sin", that was also society.
And like... Don't we have body-hair because of evolution? Guess what I do with body hair? I use wax to take it off, because it's disgusting to look at it... And like, I certainly don't think it's disgusting to see body-hair at my leg because of evolution, I think that prooooobably because of societal norms ingrained that in my head as I grew up... Or maybe because that's just my personal taste and I hate it, so I take it off, who knows? It doesn't matter, the important part is that it's not because of evolution, as evolution considers body-hair an useful feature for self-protection.
This argument makes no sense at all. Evolution affects us to some extent on a subconscious level, but that's hardly relevant when compared to what we care about on a conscious level... And even then, the core argument of life revolving around sex for the sake of reproduction kinda falls apart on its own because for as long as humans have been a thing, there have been plenty of people who were fine with not reproducing, and people who were fine not having sex.
Seriously, I dunno how you even think that, but I can assure you that you don't need to write about sex to be a good writer for non-sexual stories. You simply don't need it. You don't need to be comfortable depicting this kind of thing to create good stories with interesting and engaging character interactions in them. That's just not how those things work.
