Again you have some misconceptions about history.
"Fruit/Sugar" and carbs in general weren't seasonal, there are different sources of carbs through the entire year it's not like you just ate wild apples.
Starchy tubers, starchy nuts / seeds (the ones that you have to crush rinse to draw off nasty stuff and then cook), wild grain, berries, fruits etc. are for the most part available all year round in one form or another.
Not all fruits ripen during the same period this is why we have seasonal fruits from early spring to late summer and autumn, infact the only period when food was "scarce" is dec-feb and then hunting was out of the question also what did not hibernate migrated, what didn't do either you wouldn't want to mess with.
Additionally we became quite good at preserving food, fermentation, and sun drying fruits and other sources of carbs was commonly practiced both to preserve them as well as to break complex carbs into more simple one for high caloric value, fire cooking also changed the game because it gave us near immediate access to "refined carbs" through the process of cooking there is a reason why a cooked potato tastes sweet while a raw potato doesn't. The ability to efficiently process starch and the ability to cook it actually precedes the large explosion in tool making especially for hunting purposes, so rich caloric carbohydrates actually what gave early humans the caloric allowance to be able to hunt.
In fact I would go out on a limb and predict that you are "white" if so you owe your whiteness to the balance of vitamin d and folic acid and specifically the added folate from the daily consumption of grains, this is why your ancestors from the baltic area could keep their skin white (infact they had too) while other populations in the same parallel like inuits, eskimos and chukchi are fairly dark skinned (they need to protect the little folate they gain from their diet with darker skin while they gain more vitamin d from animal sources).
Overall we have a pretty good idea of how our ancestors ate (and this picture becomes clearer every day) not directly but through prehistoric dumps and more importantly the tools, we can know the ratio of tools that were made to process flora vs tools made to process and gather meat.
Throughout history there is no evidence whatsoever that meat made a large portion of the human diet, even during paleolithic times, meat isn't easy to gather, it's time consuming, it's dangerous and overall the energy expenditure associated with it is quite high.
The "paleo" diet in general is for the most part a bunch of horse shit, sorry folks read what evolutionary biologists actually think about it (and him, read Hillard Kaplan, Marlene Zuk, Jennie Miller and many others) , it's pretty much a commercialization of a fantasy by one man - loren cordain, which while it has some benefits it's really not a unilateral case.
Now don't get me wrong "low carb" diets can be "beneficial" on "rare" case by case basis' however the wide adoption of them isn't back to basic/nature/old way in any way shape or form, and oddly enough this is one of the most immoral diets out there.
Low carb diets are unsustainable and the vast majority of the population cannot afford them and it's good that they can't. Meat, fish, dairy and animal based fats come at a huge expense of the environment, the beef industry alone is responsible for a huge part of our energy consumption https://en.wikipedia.org/wiki/Environmental_impact_of_meat_p.... Fishing isn't good either, we overfish the oceans, inland fish farms are an environmental disaster and "open ocean" fish farms aren't much better.
While I am not a vegetarian nor do i wish to be the world would be a much better place if we all were, and one of the best thing you can do for the environment is to do 1 day without meat or any animal products ironically this would have more impact than recycling and other "feel good" activities people tend to do.
And don't get me wrong, no one says that you should eat twinkies and drink soda all day, but using pretty silly terms like "super refined sugars" and other nonsense that sounds scary and somewhat scientific is just absurd, there is very little reason for people to drop their daily carb consumption below 40-50%, but you don't need keep it at 80% either.
But somehow people have been brainwashed that one of the comments in this thread to myself equated rice to eating dry leaves, rice is one of the most nutritious foods out there, with decent carbs, fiber, some protein, and more importantly nutrients like iron, magnesium, niacin, B1, B6 etc.
And I wouldn't bang the obesity drum too hard, it's a really big unknown atm there seem to be generational changes and even with the same caloric intake some people become obese while the previous generations haven't and no this has nothing to do with "refined sugars" or "industrial food", while that food isn't especially healthy it doesn't explain the shifts in metabolic factors, the over representation of the insulin receptor genes and other epigenetic differences.
Overall reducing your caloric intake is the main thing you should be concerned about, some of the "healthiest" (based on life expectancy in various regions) diets in the world are a far cry from being low carb without showing signs of obesity.
So eat what you want, but take everything with a grain of salt, but more importantly don't base your arguments on "we need to eat less carbs because cavemen" or "we are obese because of gluten and starch" your grandparents, and great grandparents, and likely even parents ate much more carbs than you and they weren't obese.
Overall the human caloric intake has remained "flat" this includes even modern hunter gatherers (one of the more surprising discoveries of modern nutrition science) that although are considerably more active than their western / industrialized world counterparts consume the same amount and even less calories each day (this was adjusted for body mass and condition), our brains consume quite a bit of energy ;) (sometimes actually wonder if we aren't getting fatter because we are getting dumber).