You mentioned twine a few times there. Do you mean twine made from scratch from plant material? What plants? How do you prepare them?
Like I said, I don’t know much about tanning, but a requirement for ash is functionally the same as a requirement for boiling: Either way, you need fire first.
I have no objection to using sandstone to grind sharp points, though I wouldn’t call that a zeroth-generation technology. The sandstone itself is zeroth-generation, and then you’re using that as a tool to make another tool. In any event, my point there was that it doesn’t take long at all to have effective weapons.
And to what tree are you referring when you say “ironwood”? That common name is used all over the world for various local species. When I hear “ironwood”, I think Eastern hornbeam (aka musclewood, from the striations on the trunk), but you might mean something different. And I wouldn’t go after Eastern hornbeam right off the bat, anyway, since the tools needed to work it are more trouble than they’re worth (even with modern tools, it’s pretty tough).
I listed a bunch. I prefer seagrass, papyrus and the inner bark of morning glory vines for twine. Acacias for thicker rope. And you generally scrape them with something and roll them on your thigh, or braid them, depending on the fibre.
With boiling, you need a fire now. For ash, it just has to have been recent enough. And anyway, like I said, fire is no obstacle to the trained man
I know, I was just reinforcing the point. And I think you’re being needlessly nitpicky about what constitutes zeroth-generation, I mean, as soon as I start gathering reeds to make a basket and soak them to make them pliable, or start picking the bigger grit and stones out of my pot-clay, I’ve crossed over into processing just as much as if I flake the edge of a quartzite core.
Olea capensis, the Cape olive. Although Acacia karroo and various other local hardwoods are also pretty dense.
But we’re just using sticks or other easily-available bits, for knapping or for other things that need harder wood specifically. Plus never underestimate the amount of shaping you can get on wood with abrasion as opposed to cutting. More time-consuming than a steel blade? Sure, but sandstone is nature’s rasp and file.
For construction, or for hafts, or for bows, or spears, or whatever, there are other woods or plants that would be preferred. I can provide specific examples for each application, if you like. For some of them, I can probably dig up an online cite as to how they were historically used for just that purpose.