Your 50-25-25 diet seems fairly low carb to me, at least compared to what I think lots of Americans eat.
25% carbs isn't so very much, IMO.
OTOH, I think ancient men did probably not eat too much fruit, as it is mostly seasonal in temperate and cooler climates.
However, whenever I avoid sugary products for a couple days, like ice cream and soda, I greatly increase my intake of fruit and still lose weight.
Also wild fruit is very different from the fruit we have today. It was smaller, had more fiber and a lot less sugar.
Ever had a wild orange? Your mouth is stuck in a pucker for about three days.