Someone asked a question similar to this, asking "why isn't the Niger River Valley considered a cradle of civilization?"

I'm going to go ahead and link to the answer that I wrote for that question.

I'd also recommend reading follow up comments and clicking through to the linked comments of /u/commodorecoco and others.

The basic explanation holds, for Caracal, Niger river valley, or for Benin. the "cradle of civilization" narrative was popular in the late 19th century up through the 1950s, but historians, anthropologists and archaeologists have (mostly) come to believe that it is an unhelpful way to think about the past.