The first thing to when you arrive is speak with Pascal, the village leader. He is quick to assure you that his people are not hostile and suggests you look around. It's worth noting however that you will unlock Ending N if you were to slaughter all the villagers. That said, activate the access point first then check on the weapons dealer for some new gear if you like. Climb up the ladder nearby to find a Skill Salve S in the shack to your left. Heading further in the same direction, near the ladder going down are some houses you can jump on to go higher. Sitting at the highest platform is an item box with a Small Recovery.
There's a bridge on this circular path that leads to Sartre who has a quest for you. Accept that and find your way down to the lowest level of the village where a Sister machine will give you the Lost Girl quest. Speak with Pascal again to receive a Fuel Filter which must be delivered to Anemone at the Resistance Camp. While backtracking toward the Amusement Park, just passed the bridge leading to the village are some platforms you can jump on to go higher.
You'll find the Scientist Machine standing there and talking to him starts the Half-wit Inventor quest. Anyway, go hand the filter over to Anemone so she gives you some Viscous Oil to deliver to Pascal. Return to the village snd give that to him. You'll then receive an emergency transmission from command saying the city ruins is under attack by Goliath class machines. From here, there are two possible exits you can take. The one leading back to the Amusement Park unlocks Ending H, so you'll want to follow the downward path back to the city ruins.
Here, track the destination marker to the top of a building where you'll come across another Engels (the Buzzsaw Goliath). Destroy it and keep moving until you successfully locate your flight units. Once onboard, destroy one more Goliath to trigger a scene which turns a big chunk of the city ruins into a pile of rubble. Before heading down to the new cave area, visit the Resistance Camp and accept the Photographs quest. Don't forget to save your game.
Once you've dropped into the cave area, keep going forward until you find an alien ship. The fork in the path earlier leads to a locked elevator that connects to the Copied City. You cannot access that until much later in the game so ignore it for now. Back on the empty ship, head for the marker to meet the brothers Adam and Eve.
The following battle with Eve is not something you need to win, but still you must survive long enough to deal the damage required (which fortunately isn't much) to make them leave. His attacks are strong especially on higher difficulties so its probably best to hang back and let your pod do most of the damage while you focus on dodging. And try not to pay attention to 9S while he fights Adam in the background as they can be quite distracting.