Why did the Engineers create life on Earth

Rating: 9/10 (17 June 2012)

(Warning: this text may contain Spoilers) Couldn't it be possible that the Engineers were trying to move to planet Earth? If you remember, humans could breed inside the Engineers Spaceship, so it means that the humans shared the same atmosphere as the Engineers did. And we also encountered our old friend the "Alien", that the Engineers had also met before on their past trips across the Universe.
So I was wondering if the purpose of them creating life on Earth was because they studied the Universe looking for a planet with the same atmosphere as they had in their own world, and they sent one of them to our Planet to start life with their own DNA, as a trial, for them to see if it could be possible to create conditions for them to live on Earth.
And why would they do it? Do you remember one point on the movie when David, the robot, went into the heart to the Engineers ship and got to see a hologram of the Universe? Did you noticed that Planet Earth was far far away from their own World? My guess is that the were facing serious problems with the "Alien" race and they were desperately trying to escape from them by moving far away into the Universe to a Planet that would have the same conditions as their own planet to continue living without the threat of the "Alien" species.
So it would explain why they were trying to kill the Humans, because we were just a project all along, for them to see if their DNA could have a chance to survive on Planet Earth. And this is why they had decided to eradicate Human life on Earth a long time ago, because their experiment had worked and they didn't need us any longer, because they already had the answer they were looking for. And it also explains why the Engineers didn't have the slightest bond with the Human race, because we were just an experimet for them. Nothing emotional there. So, when the Enginneer awoke 2000 years after, he carried on with his mission, to bomb our planet in order to eradicate all life forms on Earth for them to finally move to Earth and continue with their kind, away from the "Alien" species.
Thoughts anyone...?