It doesn't please me to say this, but Fassbender comes across almost as Scott's carer in that interview. Scott is barely coherent at times, and whatever you think of the sci-fi usage of scientifically unsupported Von Danikenesque claims about Nephilim and xenogenesis, I for one don't care for their incorporation into the franchise. For me Alien has always been of the 'one big lie' school of SF/film-making - mankind encounters evidence of intelligent life, and living examples of an associated dangerous lifeform. I was fine with the 'engineers' harnessing or creating the classic Alien, but for me, them also being our creators, contra to all of the paleontological and genetic evidence, was a bridge too far. It's part of why I prefer Covenant to Prometheus, and didn't have (relatively speaking) such a problem with certain plot directions in Covenant; I was just pleased to get away from Scott's delusions about the ancient past.
For anyone that cares (and recognising that in the context of an SF movie, inclusion of this stuff is a personal thing), Jason Colavito has some good analysis of 'Nephilim' claims on his blog, e.g.
http://www.jasoncolavito.com/blog/review-of-the-unexplained-files-segment-on-giants-in-the-republic-of-georgia - TL;DR; it's by no means certain that the bones of people with gigantism have been found, and there's certainly no evidence for a species or community of them.
