We've lost technology constantly. We totally lost the ability to create concrete for about 1500 yrs, but nobody denied the existence of the Roman Pantheon. Which we still can't reproduce. We literally cannot create large, non reinforced concrete structures that don't crumble in 20yrs much less 2000. You're very close to a paradigm shift in your thinking. Don't ask how people could have possibly accomplished great feats without an iphone. Instead, ask now that you have one, why can't we accomplish anything. IC's are just tools, they are not self evident accomplishments.