This got me thinking: how far down the current human tech tree could a single person get on their own? It took thousands of years for humans to go from fire to the steam locomotive; could someone do it in a lifetime?

Obviously the ability to skip by basic research and dead ends would cut this down by a ton, but ultimately a lot of the things we’ve created in the past century requires a huge amount of complicated machinery to make, which requires more machines and more labor. Could a person reasonably start from scratch (let’s say skip the mining and just give them coal & metal ores) and make a Geiger tube? Or would it be too difficult?