A possible reason why Engineers spared us...

[The Alien Predator]

If one country's bio-weapons facility gets destroyed, that's not going to stop said country from continuing their projects, and that's just a country. Why would this stop an entire interstellar civilisation like the Engineers? They must've figured we weren't worth the effort and deaths so the project got abandoned for some reason. We know they were still around after Prometheus because of Covenant and are still possibly around as Ridley plans to have them show up again.

The other Engineers might not be aware of the whole situation. Maybe they think the facility is still up and running, taking care of planets across the universe.

That might be a possibility.

It's weird though since no one tried to contact the facility. Even Weyland-Yutani were able to eventually learn that one of their colonies went silent and sent Marines to investigate.

Unless they knew all along and just abandoned the place as it would've been too dangerous to go there. And the reason those Engineers were so happy to see the ship is because it is one of the survivors from the disaster who managed to wake up and escape.

[Baron Von Marlon]

That might be a possibility.

It's weird though since no one tried to contact the facility. Even Weyland-Yutani were able to eventually learn that one of their colonies went silent and sent Marines to investigate.

Weren't they in a spacestation? Perhaps once in space, it's possible to make contact with a ground station.
But direct contact between planets isn't possible because of the surrounding atmospheres or something.

I'm also thinking the Engineers don't use technology to communicate with eachother like we do, since they let David in the Juggernaut approach their city.

[SM]

Shaw's signal - albeit degraded - got through.

As did the signal from LV-426.

[bb-15]

I'm also thinking the Engineers don't use technology to communicate with eachother like we do, since they let David in the Juggernaut approach their city.

This is the key part for me.
The Engineer ship flies into the Engineer home world with no clear communication between it and the people on the ground.

Ridley Scott's commentary about this (time in the film, 1:08:20) where David flies the Engineer ship over the city.

...this is where they are welcoming him. 'Cause these things go off and come back years later. That's their role. And it's a welcoming process till something seems to be going wrong and they don't understand why...

My film theory about this is that the Engineers on Paradise (the home world) are isolated on purpose from the Engineers on LV-223 who do the seeding of DNA on other planets.
The Paradise Engineers blindly welcome a juggernaut ship with no concerns and they feel no need to know specifically about what is happening on that ship.
- By contrast the LV-223 Engineers have a detailed map of planets in the galaxy which indicates that those Engineers do have an idea of what worlds were visited by certain Engineer ships.

[Baron Von Marlon]

My film theory about this is that the Engineers on Paradise (the home world) are isolated on purpose from the Engineers on LV-223 who do the seeding of DNA on other planets.
The Paradise Engineers blindly welcome a juggernaut ship with no concerns and they feel no need to know specifically about what is happening on that ship.
- By contrast the LV-223 Engineers have a detailed map of planets in the galaxy which indicates that those Engineers do have an idea of what worlds were visited by certain Engineer ships.

I agree on the different purpose but not on the purpose.
I think the ones on LV-223 do the destroying. And the ones in Paradise, I don't know. At first I thought they did the seeding.
But the seeding ones used a big black ship that seems unfit for the Paradise landing zone. So perhaps they're from a different planet and the Paradise ones visit planets after the seeding.

[SM]

Couldn't the teardrop ship from Prometheus fit vertically into the docking ring?

[Iron Infililtrator]

Weren't the Engineers in a cryosleep because of the goo escaping though? It kept them lost for many many years. There's probably a reason why the rest of the planet came running to greet the ship in Covenant.

[Baron Von Marlon]

Couldn't the teardrop ship from Prometheus fit vertically into the docking ring?

The size of the Teardrop seems similar in size to the Scorpion. Maybe even bigger depending on how high those mountains below are.
I don't think it would fit.

[whiterabbit]

I think LV223 was their WMD delivery facility for our sector in space. Think of space as an ocean and a planet like a submarine. I'm mean honestly, no matter how peaceful one chooses to live, there is always the risk of someone else trying to kill you. I wouldn't be surprised if over the eon's engineer societies lost touch with each other yet still kept some sort of "on the ready, self defense" force intact.

In Alien the engineer sent a distress call saying to avoid the planet it had crashed on. It wouldn't be odd if the same transmission was sent after the catastrophe on LV-223. The reason the Prometheus didn't detect the message was because they weren't aware of the engineers communication techniques. Such as the snowy holograms. I take that snow to only mean that our eyes were not designed to see the entire picture. Now why the Covenant could detect it? It's been ten years, perhaps the people of Earth made upgrades. I don't know.

As far as sparing us, it is clear that the engineers made at least 2 trips back to Earth after the events of 2000 years ago. Which can only mean one thing. Hawaiians are Engineers.

[Corporal Hicks]

If one country's bio-weapons facility gets destroyed, that's not going to stop said country from continuing their projects, and that's just a country. Why would this stop an entire interstellar civilisation like the Engineers? They must've figured we weren't worth the effort and deaths so the project got abandoned for some reason. We know they were still around after Prometheus because of Covenant and are still possibly around as Ridley plans to have them show up again.

The other Engineers might not be aware of the whole situation. Maybe they think the facility is still up and running, taking care of planets across the universe.

2000 years is a long time to go without communication. I would have thought they'd be some sort of chain of command externally and a lack of communication should have raised an eyebrow.

[Predaker]

They could have a caste system as part of their civilization, where not everyone is privy to what exactly goes on outside their homeworld.

[Corporal Hicks]

They could still have some sort of military command structure. Unless that was their command base - but given the nature of the experiment and it being a weapons testing facility (if Janek is right), I'd imagine it'd be some isolated place and not the home of their Generals and etc.

[Baron Von Marlon]

They could still have some sort of military command structure. Unless that was their command base - but given the nature of the experiment and it being a weapons testing facility (if Janek is right), I'd imagine it'd be some isolated place and not the home of their Generals and etc.

Then maybe it is a rogue faction, out to destroy the creations of the "good" Engineers.
If one ship's cargo was enough to destroy Paradise, it'll probably be enough for Earth.
So maybe the other ships on the Prometheus planet had different targets.

I keep thinking of that movie The Prophecy. Rogue angels jealous of the creations and trying to destroy them.

[irn]

With the time it takes it move around in space there is probably very little central coordination.

[Corporal Hicks]

With the time it takes it move around in space there is probably very little central coordination.

I see what you're saying but there would have to be some sort of communication infrastructure or policy. It'd be foolish not to be communicating at all. Even if was just a simple - we're still here, here's our latest reports as of 2000 BED.