Be Excellent To Each Other

In order of appearance:

Character dies of starvation immediately.
Plenty of charred innocent civilians from the allied firebombing.
Main character's mum is horribly burned.
Main character's mum dies shortly thereafter. The body is festering with maggots eating the flesh and the orderly at the hospital exclaims loudly in front of the son that he wants "it" out of the hospital.
MC doesn't tell his sister that her mum has died.
MC gets screwed over by his aunt who take most of his possessions that he was clever enough to bury before the firebombing.
MC's aunt is a bitch.
Aunt is more concerned with selling his dead mum's clothes for rations.
She does and then she refuses to give MC and his sister rice because they aren't helping the war effort.
Some other thoroughly miserable stuff happens.
MC's sister gets really sick.
MC's sister suffers from malnutrition and the doctors refuse to help.
MC can't get any nutrition because of the war.
MC finally gets some food! Sister dies before he can finish cooking it.
MC sleeps with his dead sister because what's he going to do the body? He's a kid. Dead corpse sister fully on display.
MC finally gets some fuel to cremate the corpse. Has a nice old time carrying his sister about and boxing her up.
MC shoves his sister in a sweetie can.
MC dies of starvation.
Nice bloke who is cleaning up the dead bodies of children who have starved then throws MC's sweetie can filled with dead sister in the garbage.

THE END.

I've read that the story is based on a semi-autobiographical account of the boy and that the scene where his sister carks it is accurate to what happened in the story. I assume that the scene in the film is accurate to the story which makes me upset just thinking about it.

The decision to head to the new planet was a sound one. It was closer, and clearly habitable. So good choice there. When they arrived in orbit it was clearly covered in vegetation and water, so a fantastic, and massively unlikely find. Yay for team Covenant.

Investigating a crashed ship is not an unusual thing to do – and indeed is precisely what happened in Alien, so unless we’re undermining the whole franchise, that’s not completely stupid either. So it was not astoundingly stupid to go and have a shufty on this new planet hat was only slightly out of their way and investigate the signal and the crashed ship at the end of it. So all good there too.

Biologist woman dragging infected man back to the lander was not completely stupid either – what else are you going to do? Pilot lady was right to lock them in the med bay.

David’s intervention was something that clearly came as a WTF, but they had an explanation as to why he was there – they knew about the missing Prometheus. It’s non-obvious that a synthetic would be a massive, massive psycho with daddy issues so following a familiar face was not insane.

The only specific two things I can think of that were stupid are (a) that pretty lady going off to have wash on her own and (b) religious replacement captain following the now-obviously insane David down into a cellar, and then sticking his face in an alien egg.