I love it when this franchise introduces other alien races. My favourite bit from Fire and Stone is the panels that show Ahab hunting various aliens throughout the years. The four armed red skinned tribal aliens, the more advanced bug like race with technology that may be decades away from us currently, and then finally this race that wore full futuristic body armour and had holographic technology showing an Engineer.
This is why I loved Prometheus so much, it opened new doors for the franchise and has given us a perfectly valid excuse for why some aliens can be similar to us. I bet Engineers created Arcturians too.
We never knew what the Arcturians from "Aliens" were, many thought they were human colonists on Arcturus. That it was the red light district of space where Colonial Marines went to let off some steam.
But Sea of Sorrows confirms that the Arcturians were the first intelligent alien race that humanity met. Since then, my curiosity about the Arcturians has went through the roof. They were mentioned in River of Pain as being "Trading Partners" with humans. Tim Lebbon has also teased that he will mention the Arcturians but not feature them.