I don’t think there’s any guarantee that civilization would rebound. Fossil fuels were a one-shot deal in the geological history of the planet. For all of our efforts to build a sustainable future with renewable energy, fossil fuels remain critical for a lot of non-energy uses: food production (fertilizers), plastics, steel, and even cements for construction.

Another major issue is critical minerals for building renewable energy infrastructure. These minerals are being mined at an incredible rate, processed and turned into technology (think circuit boards full of components), aging out, and ending up as e-waste. Unfortunately our e-waste recycling infrastructure is a total nightmare involving the shipping of this stuff across the ocean to 3rd world countries where it gets picked over, scavenged for valuables, and the rest turned into toxic landfill.

All of that technology lifecycle creates huge amounts of toxic pollution and consumes huge amounts of fossil fuels (in particular for the mining, processing, and shipping). So in fact without fossil fuels we don’t even know how to build any technology, let alone renewable energy.