So we were not alone - and neither were the Engineers

Another thought and theory... So Prometheus went to search other life with only one star map in tow directing them to only one place. Now what if there were other lifeforms out there and the Engineers had been to visit them also and done the same thing with them as they had with us? Perhaps, just perhaps they had been to many planets, given birth to many lifeforms, and had been checking up on them periodically to see who was most suitable to be used for the furthering of their species. therefore the 'Deacon' was seen as the supreme evolution from whoever they chose. The epitome of the supreme breed. Where we were all guinea pigs used to get there. When we were the first to come knocking, and it had become apparent we had become gods ourselves, it sealed the deal. We had to be put in our place. It just strikes me as a bit of a 'needle in a haystack' situation that of ALL the planets in ALL the star systems it is 2 years away in a spaceship for us to be the only ones. There may have very well been others 2 years in any other direction from LV-223 that they had seeded life to