Carrying The Fire by Michael Collins is an excellent account of Apollo 11 from the perspective of the command module pilot. I've read it three times, it's a wonderful book, he's a very intelligent, capable and humble man.
As test pilots they were extremely competent technicians obviously, but they were expected to develop in novel individual domains to solve previously unexplored problems. By the end of gemini the first two dozen astronauts were each among a handful of world experts in their focus: things like orbital rendezvous mechanics, navigation, interface design, biomechanics of flight, radio telemetry. The program wasn't built for them to fly, to a huge extent they guided how it was built.