Representative John Lewis, who died Friday at age 80, will be remembered as a principal hero of the blood-drenched era not so long ago when Black people in the South were being shot, blown up or driven from their homes for seeking basic human rights. The moral authority Mr. Lewis exercised in the House of Representatives — while representing Georgia’s Fifth Congressional District for more than 30 years — found its headwaters in the aggressive yet self-sacrificial style of protests that he and his compatriots in the Student Nonviolent Coordinating Committee deployed in the early 1960s as part of the campaign that overthrew Southern apartheid.