Until the industrial age, I think fire was less about having more energy to work with and more about things that could never be done with any amount of mechanic

Until the industrial age, I think fire was less about having more energy to work with and more about things that could never be done with any amount of mechanical power: heat, light, cooking and all its many benefits, repelling nocturnal predators, and transforming available materials in many useful ways (including smelting but also e.g. fire-hardened wood). It did also replaced mechanical energy in some ways, e.g. hollowing out bowls or canoes, primitive mining by using large fires to crack rock faces. But I feel like those are less transformative than the other effects.