You have no idea what you're talking about.. You might as well tell me the moon is made out of cheese.
Nor, apparently, do you.
I'm not going to address every point you have made in each post, because that requires too much work on my part, selecting different quote sections from various posts. It's not important enough for me to prove you wrong.
That also means I am not going to do your research for you and make a list of citations. I'd actually enjoy doing that, to a degree, but I am just feeling way too lazy.
First, you don't NEED a ton of carbs. Do you need carbs, period? Yes.
Zero carbs is an almost impossible nutritional goal anyhow.
All the best non-meat protein sources have a fair amount of carbs, and the whole package equates slow digestion, which is ideal.
And you are opening up a whole different can of worms by comparing what our body is genetically designed to do, and what we are trying to do today. There are almost too many factors to really compute, making it difficult to create a perfect diet (flavored goop food-substances, here we come!) for whatever you decide to do.
First off, modern athleticism and the genetic history are related, but not twins. Even dating back to the Greeks and beyond, competitive athleticism goes above and beyond what any early specimens would have accomplished.
They competed for attention, for tribal rule, for mating, but they didn't hold massive competitions and go running for pleasure across 20 miles of random terrain, just because it sounds like a fun idea.
That necessarily changes required dietary intake. They weren't being chased every other hour, worried sick every time they took a nap, or what have you.
Early, primal, haven't-left-Africa-yet humans, sure... they may have. But even then, such encounters were not likely an every day occurrence.
As a society, becoming adjusted to dependable food sources, regardless of their actual net value, is a necessity - especially when moving to new territories. Especially when your tribe is no longer 20-50 strong, but thousands or larger. You either begin to limit the size of your local society, or you spread out, or you adapt as best you can with the knowledge you have.
It turns out, we can
survive on a hell of a lot. There is a large difference between surviving, and living in ideal peak condition. Even ancestral humans weren't all perfectly healthy or in peak condition, that likely varied quite a bit. Your social standing and the relative wealth of regional resources played a large role in that regard, most assuredly.
You'll notice I also stated, at some point, perhaps even in a different thread, that you should shape your diet around your average and specific activity levels. If you are training or preparing for major athletic events, it's a good time to stock up on more carb-rich foods. Still, of the complex variety... not shooting up liquid sugar.
But you should rarely, if ever, consume anything that has more carbs than any other nutritional component, unless you are planning to biologically utilize those relatively worthless empty calories in the immediate future. If you compete at noon, for example, you really shouldn't be consuming any grains or otherwise carb-heavy foods after that event. Some carbs, in a protein- and MUFA/PUFA-heavy food source post-event, is good to shore up biochemical energy to most effectively conduct various biological reactions and get the more-important chemicals where they are most needed; but even then, that's of today's knowledge, and all in the effort to SPEED-UP the natural processes. More efficient, perhaps, but we still aren't entirely sure at what cost.
The body is "designed" to handle just about anything, specifically for short periods, so that it can survive to see another day, at which point hopefully with better luck at getting what the body really needs. Just like we can go days without quality vitamin intake, because the body can handle short-term deficits and surpluses, is, again, "designed" to be able to handle that so that life isn't more of a struggle than necessary.
The brain and body needs carbs, sure, but even completely giving up grains, you won't be struggling to even reach 100g of carbs in any given day. You may even surpass that without grains.
The FDA, based on subtracting what they call "limits" for average fat and protein intake per day, basically sets one up to consume over 300g of carbs a day! Honestly, that's all kinds of ridiculous.
You can mentally prepare yourself to "drastically cut back on carbs" - and go over 100g, if not 150g, and shit yourself when you realize you consumed that much even when actively trying NOT to do so. Especially with modern foods, carbs are in everything. Even eating completely whole foods, nothing processed, you'll find a healthy amount of carbs in your average daily intake.