Recently I was wandering if there is someone or some group preserving , collecting , organizing and publishing all the knowledge of mankind ever created throughout its existence so that if ever mankind faces the 6th mass extinction we don't have to reinvent the wheel and can have a kick start to our new post apocalyptic civilization .
That is pretty much exactly the goal of the Wikimedia Foundation which runs Wikipedia and its sister projects.
But by now we figured out what wikis can do well and what not. Wikis are suitable for crowdsourcing objective facts about the world (all it takes is one person to add any given fact), they are not a universal remedy for everything, especially not contentious issues or useful instructional materials.
I have made more than 100000 edits to their projects. I don't participate there anymore. The time when they were a force for good in the world is long past.
Their goal isn't to collect all human knowledge, only notable human knowledge.
See https://en.wikipedia.org/wiki/Wikipedia:Notability and https://en.wikipedia.org/wiki/Wikipedia:What_Wikipedia_is_not#Wikipedia_is_not_an_indiscriminate_collection_of_information .