I can contribute, I got some ^^
Also, op, that's the Deacon. It's what Ridley Scott shoehorned into the 27th rerwrite of the script when Fox wouldn't let him put the Xeno into the movie.
TL:DR: It's not the origin story of the Xenos, it was just to showcase that the genetic code of the xeno is so powerful that it will attempt to turn whatever it's in back into a Xeno because "it's the perfect biological form"