To me, Holden is a man playing a role anyway. His family told him that he had this responsibility to protect and perpetuate and he's trying to live up to this. However, in many ways, he's painfully naive and is making it up as he goes along based on a completely wrong-headedly optimistic view of humanity and human society.
Jim Holden is a man doing his best despite being utterly out of his moral depth. In that, he is engagingly real. Paladins don't really happen and there is something engaging about seeing a man struggle to be one in a universe that is utterly inimical to one.
I think that they gave us a huge clue to the real Holden in season 1 when his mother told Avarasala that his favourite book was Don Quixote.