That having God in the final episode of Quantum Leap (the original) being played by an actor who was also in the first episode of the series made it much more interesting.

I hope you mean the original series and not the reboot. I don't think he ever admits that's what he is. My personal belief is that Captain Braxton of the Relativity was lying through his teeth to Sam (in order to preserve the Temporal Prime Directive), and directs him to the biggest Leap of his career, Captain Jonathan Archer in the First Contact timeline, because that whole timeline represents "what once went wrong".