My theory about the link between Paradise and planet earth.

[Xenorgue]

It is no coincidence that the crew of the Covenant discovers on the planet paradise, wheat, trees and mosses. We all know that these organisms are Earth-specific. It is normally impossible statistically that a fauna similar in all points to the Earth appeared on another planet. Except if we add engineers in the equation then everything makes sense.

The engineers worked on terraforming or rather on Paradise transformation. The Earth was only a desolate and empty planet. The engineers have to terraform the planet earth for that it can receive the descendants to the engineers: The humans. Once the planet transformed, the engineers came to the planet to fertilize it. (Beginning of Prometheus). That is why the temple in prometheus was breathable, because engineers are capable of transforming planets into their worlds. All the trees and all the fauna we know on earth comes from their planet and the Earth has been terraformed by the engineers to welcome us.

For me this theory would explain EVERYTHING ! Why we find terrestrial plants on Alien Covenant and the link between our planet and that of engineers. The earth is only a creation of engineers to resemble their planet.

[The Alien Predator]

Even in the older stories, there are some very terrestrial looking animals. I remember an Alien comic that literally had a Jaguar looking creature on another planet.

Plus the AvP2 game mentions that the DNA of the animals on that planet was very similar to Earth animals (which is why the Xenomorphs born out of them were similar to the types we usually see such as Runners etc.)

And that world had Space Jockey ruins and was breathable for humans.

Sure, the similarities are a coincidence as these works were done way before the concepts of Prometheus and Engineers came into being, but looking back at them now, they could very easily tie into the current stories of Engineers terraforming worlds and seeding them with very familiar and similar life.

There could easily be more human looking aliens in this franchise on Earth like worlds, and it won't be odd or out of place because the Engineers would be the missing link that binds us all.

Plus the Black Good when analysed in Fire and Stone had many kinds of DNA including some very recognisable terrestrial ones.

[Xenorgue]

Even if I love the extended universe I do not consider it to be a canon.

Thinking about it, the Earth is for me an experience of terraforming engineers. The engineers thus export the flora and fauna of their planet on Earth.

The Earth is thus in the image of Paradise.

Why have they sown the earth? May be to preserve their species from war through the human being. Maybe the earth was only a petri dish to cultivate the xenomorph?