Physically, the adverb says how you come down: 안전하게 내려오다 "land safely", 너무 빠르게 내려오다가 "coming down too fast". On a map it becomes extent — 이탈리아가 쭉 길게 내려와 있죠, "Italy stretches a long way down". The extra sense worth knowing is inheritance: 구전설화처럼 그렇게 내려오는데 means a story handed down through the generations, which is what 내려오다 does with traditions and legends.