So the stone age IMO is way to short in this game, and i think that's also the reason people have a problem with foraging. The part of the game where Hunter/Gatherer lifestyle is most useful is such a small fraction of the playtime even though it is the largest period of human history. Alot of people may say that's just because there isn't alot of content you can have in the stone age but they are completely wrong.
The Stone Age went through several major technological changes across it's nearly 2 million year lifespan and i am only going to focus on changes that effected the most recent human species, The Homo Sapiens and The Neanderthals (even though underdeveloped hearthling skulls are Homo Erectus Skulls, so there is an argument to be made for Homo Erectus being the start point of stone technology) So we should probably start in the Lower Paleo-Lithic (Beginning of Neanderthals and Humans) where stone tools consisted of only an axe head, which would be swung using your forearm as shaft instead of having a wood shaft and these hand axes were made by taking a stone and knapping it down into a head. These were in general the lowest quality stone axes as they were really the first technology of them.
In game what this would probably boil down to is just chipping one stone off of a boulder and then crafting that stone into a handaxe which would have no damage and major quality restrictions.
I'm thinking for Handaxes it should be either Raw Survival or Survival + Int that determines quality and Quality should be majorly nerfed on these. It would just be a starting tool.
After this there should be a skill you can learn for X amount of learning points called "Middle Paleolithic." Or "Advanced Stone Tools."
In the Middle Paleolithic is when something quite revolutionary happened. Neanderthals discovered the ability to mass produce high quality stone tools. How it is done is you take a Core stone which has a flat edge and then take a smaller stone called a Hammer stone and you hit the core with the hammer right on the edge of the core causing it to shatter on the edge like glass. This force get's carried down the edge of the core stone and breaks off a major piece of the core. This broken off piece has a phenomenally sharp edge and since it's flat due to striking the flat side of the core, this piece is PERFECT for a stone tool.
In this era once you learn the skill you should have access to a new toll called "Hammer Stone." and you should be able to use it to turn stones into Handaxes. This wouldn't have the nerfed quality and would be soft-capped by the quality of the Hammer Stone, plus your Int + Survival. Also in this era of the game is when hunting weapons should become availavle, primarily Spears.
I would say we would need Stone Spears to be able to be made which would be a MM and Melee weapon prior to Bows and Swords, or weaponized axes.
The Upper just saw more innovation into this core production so for purposes of the game lets skip to the Mesolithic. The Mesolithic is when most people started using wooden shafts on their stone tools (even though their are examples of wooden shafts from the upper paleolithic, it wasn't common) and when lumberjacking started to take off. To reach this Era you should have to research another skill called "Wooden Shafts" or some equivelant. This era would be when the normal stone axes of the game we have right now, would become available to build and they would be able to chop down trees (hand axes couldn't they were used for butchering and cutting brush, which i assume in game early game butchering would be there purpose) as well, in this era Lumberjacking and other similar skills should become available, but not carpentry. Never made sense to me that the moment you learn how to chop down trees you can learn how to make advanced housing structures. For now housing would be made from Hides and wood blocks or from Mud and wood blocks and they would function just like a house but with much less space and they would deteriorate very quickly.
After the Mesolithic was the Neolithic which is when people completely dropped the idea of mass producing stone tools and went for pure quality, favoring the idea of grinding stone tools. They would have a large grinding stone and wet it down and then began the long process of taking larger stones and grinding them into too shapes. I would recommend that you have the ability to grind a boulder (just like a runestone or quern) into a grinding stone, which would function like a pottery wheel but for stone tools. This would allow for the greatest quality of stone tools as well as for new types of stone tools like Stone Pickaxes, which could be used as a transitioning tool into the bronze age. As well as this is when bows began becoming popular (i would recommend that the archery skill be obtainable after the lumberjacking one, making it so you get access to the bow recipe as roughly the same time as this technology) and anything stone, including stone arrows could be made at a grinding stone for higher quality (this also might help a little bit with early game MM since higher q stone arrows wouldn't nerf animal hides quite as much)
The Biggest thing here is i would like to see more technologies and more phases of the stone age, cause as it is it's really short and i kinda don't like that. I'm not saying these exact things should be implemented i am more giving an idea of what the jumps between stone age technologies looked like and different stages of the stone age the Devs could use if they decided to extend the life of the stone age. The Stone Age is also when Foraging was most useful in game and real life, and if we added ALOT more forageables on top of everything else, it would mean that the Stone Age in haven could be a really fun age of wondering from place to place and gathering resources, instead of the 3 day period when you are prepping for the bronze age, which is what it is now. As well as, it would buff foraging because people would need to put alot into Surv and Exp early game in order to be able to push out of Stone Age and that would mean when people get to farming they would have Very high Surv and Exp meaning forageables for awhile would be way better than their agriculture which would extend the life of foraging even into the bronze and iron age, although obviously foraging would begin to be phased out with the iron age (which it should be, no reason to be foraging when you have fucking steel xD)
Also for any of this too have a point (with stone tool quality being a big part of this whole thing) we would need it so that chipped stone from boulders wouldn't be base quality 10, it would have to very.