The knowledge a person can acquire and bring to next generation is key here. The more organized, free and widespread this knowledge is, the higher the probability it will survive.
Knowledge has been an is still treated as secret and exclusive. If the 2-3 people with this knowledge dies, we have to rediscover it.
This is the bottleneck human kind faces time and time again
Without wisdom, all is for naught. Consider internal combustion engines. Within the ICE is a long range agglomeration of knowledge and techniques ultimately allowing it to be produced in inconceivable quantities. It has also been incredibly harmful in more ways than one, the most salient and widely agreed upon being climate change.
And of course such inventions of knowledge don't act alone, and they independently have large effects, but are also affected by other factors, for instance empirical medicine has had a tremendous effect on population size, and that has in turn spurred more demand for more ICEs which has fed into the gross consumption of fuel products, and in addition obviously the production of byproducts like greenhouse gases. It also prompted what I would classify as a pretty significant terraforming project in the development of infrastructure. It also remodeled society.
Without hazarding inductive error in an ineradicably complex system which exists in in "infinite" timeline both in the context of the fractaline nature (e.g. shoreline paradox) and the sheer quantity of nonparallel time, this is important when considering the probability of black swan events. As an instance of this Benoit Mandelbrot reviewed the Black Monday data, finding that the vast majority of movement in the market occured in a window of about 10 seconds (if memory serves) And Black Monday itself was a small fraction of a year, of a decade, but nonetheless has an outsized effect.
Without meaningful prescience of what will unfold as a product of snowballing knowledge (not to mention the signal:noise) it's very probable that humanity will endure the treadmill or worse be rubberbanded back. Development shouldn't really be looked at in absolute terms, but relative. We increase carrying capacity of some natural resource and just as quickly stack the burden back up. And using a historical lens is dubious, hazarding some calculated risk whose contours we're actually unfamiliar with, and that is something humanity is accelerating with the novel technologies we're wont to spin off.
These things are the result of knowledge, but without some perspective wisdom to guide it, it is dangerous. And I would argue that wisdom is not something that can be transferred. It's the hard-fought and learned but not taught sort of understanding. Humility, compassion, understanding. Knowledge is hubris, dispassionate, and myopic.
All that to say that knowledge isn't the key. It is a tool, but it is not the principal tool. It is also not the principal bottleneck.
Knowledge has been an is still treated as secret and exclusive. If the 2-3 people with this knowledge dies, we have to rediscover it.
This is the bottleneck human kind faces time and time again