Whilst I agree that it's probably fake, why wouldn't an alien have the same basic anatomy as humans?
In many cultures there are tales of the 'gods' breeding with humans - the Christian religion is centred around the offspring of a 'god' and a human and there are accounts of angels breeding with human women (their offspring were giants). The story of Noah is based around God's anger at the peoples of the earth - maybe the reality was that God was peeved when he realised just how many of his angels had been coming to earth for a bit of rumpy-pumpy & decided to wipe the slate clean?
In Greek Mythology, Zeus was very fond of human women and the Egyptian pharoes were revered as Gods (because some were supposedly the offspring of a god/human relationship).
Of course, when you have a species scrabbling around in the muck with bows and arrows etc, any being with advanced technology would seem as a god?