With so little information, we can only speculate.

1. The aliens are losing a war. Hence the emperor flagship was in orbit around Earth.

2. Their enemy found them and destroyed the emperor flagship.

3. They are looking for their prince.

4. The dead child is not the prince.

5. The Biblical quote about the Faith.

6. The Buddhism belief on Fate/Destiny.

Things to remember

1. It is set in the 70s, likely in the mid to late 70s, South Korea.

2. Hope town is on the East Coast, bordering the DMZ.

3. The mother of the dead child was the one who attacked the town.

4. There was also another child in the basement of the ship.

Analysis

1. They're desperate to find the prince because they're losing an intergalactic war.

2. They probably have a legend that their prince will be born on Planet Earth.

3. Earth was probably their secret vacation spot. It's far from their territory.

4. Eons passed, their species on Earth evovled into Humans, or intermingled.

5. The Prince they're looking for is that 2nd Cousin. The one who just wouldn't die.

Remember they were talking about Faith and Fate

1. They will need faith to see things unseen. That's realizing who the Prince really is.

2. They need to make him realize what his Fate/Destiny is.

3. The Prince needs to accept the Warrior's heart to unlock his Fate. But it will take a leap of Faith to do so.

4. That's why he just wouldn't die.

5. Now he has to fight for Earth and the aliens.

And ironically, the Prince they're looking for is living on Hope town. He's the only hope of the aliens and Earth. Especially now that the enemy of the aliens followed them to Earth.

Q: Wait, the dead kid is the prince!

A: I highly doubt it. The one who pursued in search for the dead kid was the alien who attacked Hope town. That alien was crying and desperate. She was very attached to the kid. Thus, it's not likely the kid is the prince. The prince has to be from the emperor's line.

Secondly, there was another kid in the ship's basement.

Thirdly, there were other aliens who looked like that crying long-haired alien.

I think those aliens are breeders. They're meant to replenish their species. That basement was a breeding system.

Q: Why can't humanity be the one who destryoed the emperor flagship?

A: Because it's not possible. Remember this is set in the mid to late 70s.

Even today, 2026, we are not capable of destroying that flagship. It was huge and very highly advanced.

Q: How about nukes?

A: That's possible. But it will still take a huge miracle for those nukes to hit that flagship. Those aliens are warriors. And that ship was the emperor's flagship. They wouldn't let it get destroyed just like that.