Astronauts back then (no disrespect intended for the later or current personnel) were a remarkable group of people.
In the very early stages of selection, many ideas were thrown around as to what type of individual should be selected for space exploration. Even Poets or Artists were suggested. I’ve read Eisenhower had to cut through all that nonsense, and declared that astronaut candidates would initially be selected from a pool of military aircraft pilots, his thinking was they were the only career field that made any sense due to the experimental and highly technical nature of the job. So they were drawn from aviation and particularly (mostly?) carrier naval aviators as a class, and further refined from the test pilots within that group. There was no shortage of volunteers.
At the time it must be remembered the American rockets had a regular habit of blowing up on the pad. I’d probably do a little praying myself. And who wouldn’t be a little humbled flying 225,000 miles away from the planet, and see your home, the entire world, everyone who ever existed or would exist - as a tiny blue dot floating off in the distance? I think it was Bill Anders on Apollo 8 who started reading from the Bible on Christmas Eve 1968 orbiting the moon with Frank Borman and Jim Lovell. Anders isn’t a preacher or anything like that, but he sure did a fine job on that. I vaguely remember seeing that live as a little kid. I thought it was great, but I couldn’t figure out why Grampa was crying. So they did a lot better than some goddamn Poet anyway ya slice it.
Most of the blowing up on the launch pad was in the mid and late 50s. By the time of Mercury, Gemini, and Apollo, we were mostly beyond those early problems. If they were still blowing up with the regularity of the 50s, we would not have had manned space flight.