The most famous book (and movie) about the early days of NASA is "The Right Stuff" and it is surprisingly faithful in its telling. Alan Shepard did pee in his suit and then say, after three hours of being immobilized in a tiny capsule, "Why don't you just fix your little problem and light this candle?" but he was also a guy who said, "You know, being a test pilot isn't always the healthiest business in the world" so he understood the risks. 96% chance of survival was acceptable risk.
The book was also faithful in the debate over the capsule. Werner von Braun and his team of engineers did believe the occupant was just that - a person they would put in space - and the technology would handle everything else. They were to actually have no input at all. The test pilots nee astronauts, college-educated all, objected and, due likely to their runaway fame in pop culture of the day, won the dispute.
Here is how the capsule ended up being designed
You have to click on it to see it but you don't need to - there is no way you want to get in that thing, especially because, as they said, all the parts were made by the lowest bidder. What you don't see in this original document that made its way into the final version was any kind of 'abort' handle. The pilots had that put in.
The pilots were also given a measure of flight control, basically a fly-by-wire mode. Here is the 1959 diagram of that:
Here is the scope display and earth path indicator Shepard used as navigational aids:
And all put together: