As a man, he was "merely shallow and clueless"

"Arendt dubbed these collective characteristics of Eichmann ‘the banality of evil’: he was not inherently evil, but merely shallow and clueless, a ‘joiner’, in the words of one contemporary interpreter of Arendt’s thesis: he was a man who drifted into the Nazi Party, in search of purpose and direction, not out of deep ideological belief." 

~ Thomas White

"What did Hannah Arendt really mean by the banality of evil" 

https://aeon.co/ideas/what-did-hannah-arendt-really-mean-by-the-banality-of-evil

"Arendt never did reconcile her impressions of Eichmann’s bureaucratic banality with her earlier searing awareness of the evil, inhuman acts of the Third Reich. She saw the ordinary-looking functionary, but not the ideologically evil warrior. How Eichmann’s humdrum life could co-exist with that ‘other’ monstrous evil puzzled her. Nevertheless, Arendt never downplayed Eichmann’s guilt, repeatedly described him as a war criminal, and concurred with his death sentence as handed down by the Israeli court. Though Eichmann’s motives were, for her, obscure and thought-defying, his genocidal acts were not. In the final analysis, Arendt did see the true horror of Eichmann’s evil."

~ Thomas White