Well, the short answer to your question is that every quote is important - what we are presented with in short stories is a very concise choice of words carefully crafted together to achieve a specific effect. Okri in this excellent short story is keen to present us with a realistic picture of a war-torn post-colonial African nation still bearing many of the scars of its colonial past. Consider this quote which includes some of the details you mentioned:
He passed unfinished estates, with their flaking, ostentatious signboards and their collapsing fences. He passed an empty cement factory: Blocks lay crumbled in heaps and the workers' sheds were deserted. He passed a baobab tree, under which was the intact skeleton of a large animal.
Notice how the word choice or diction gradually builds up a picture of a decaying, abandoned and deprived nation: "unfinished", "flaking", "collapsing", and "empty" clearly paint a picture of the kind of colonial legacy that has been left and is plaguing so many African countries, whilst the inclusion of a skeleton that has lain there for so long adds a slightly menacing, threatening note, as well as indicating the kind of place this is - no one clears away dead animals - they are left to rot. In this arena of disregard and neglect, acts of violence are able to be committed and become part of every day life.