Set aside for a moment the fact that Captain America didn't die during the events of the Civil War comic from the mid-aughts and engage once again with your outrage that movie Cap didn't die during the events of Captain America: Civil War. Everyone just sort of assumed that Cap was going to die since he was killed in his first issue back after Civil War, but the Russo brothers never intended to kill the character in the film.
During an interview with IGN, the brothers and MCU head Kevin Feige explain that killing Cap would've ruined the drama surrounding the events of the film because it would have forced the two sides to reconcile faster than they would have liked...
Feige said, “Um, we never talked about killing Cap in this, right? No.” Anthony Russo answered, “We did for a beat, but we talk about everything…we do talk about every possible scenario, over and over and over again for months and months. So yeah, we had talked about it. It would never have made it’s way into a realistic version.” They explained that this film’s goal was fracturing the team completely before Infinity War.
He continued, “We actually talked about lots of potential characters dying, but that it would undercut what was really the rich tension of the movie, which was that it’s Kramer vs. Kramer. It’s about a divorce. And if somebody dies, it would create empathy [from the other characters], which would change [things], and allow potential repair. We didn’t want to do that.”
This does make perfect sense and is far more dramatically interesting than just killing him off. This is likely why Marvel continues to do better than DC, because they don't seek to be slavishly faithful to the source material.