That time period in Britain didn't just see big advancements in industrialization, but in engineering, medicine, finance, and legal systems. You have to see the difference between individuals and the the society itself.
It’s kind of silly to argue the “intelligence” difference between someone who can build a nuclear power plant given a society with supply chains available and someone who with fifty or a thousand men can go into the wilderness and build a functioning city with little or no foreign input for years. They’re entirely different skill sets.
Each year brings our “current” technology level further and further from “if you have some hand tools you can restart”.
And it’s not clear to me that importing everything into a country is a better method than letting them build their own infrastructure using what they have locally (eg only import knowledge). See the “clothing and food dumping” problems in Africa.
No one person knows everything needed to build a nuclear power plant, but as long as there's enough people who understand the different principles and disciplines required then yea they could restart with just hand tools. Knowledge is the key, the tools are not.
