Meaning of 江山错落. 人间星火
I don't think we can translate the two phrases word by word, as they are delivering an artistic message through singing.
The songwriter is trying to draw a vivid scenery in the listener's mind - at a star-covered evening standing on the hill looking down on the mountain surrounded village below, the scattered lights are glowing; alongside the village, the lazy water is slowly flowing in the river, so calm and peacefully beauty.
Wish this makes sense.