What was the original religion of the Ghana people?

Answer 1

The Ghana Empire or Wagadou Empire[1] (existed before c. 830 until c. 1235) was located in what is now southeastern Mauritania, and Western Mali. Complex societies had existed in the region since about 1500 BCE, and around Ghana's core region since about 300 CE. When Ghana's ruling dynasty began is uncertain, it is first mentioned in documentary sources around 830 CE by Al-Kwarizmi.[2] The introduction of the camel, which preceded Muslims and Islam by several centuries, brought about a gradual change in trade, and for the first time, the extensive gold, ivory trade, and salt resources of the region could be sent north and east to population centers in North Africa, the Middle East and Europe in exchange for manufactured goods.

so it is probably Islam.

Answer 2

They believed that one God ruled over them and other gods were a part of their daily lives. They also believed that doing religious ceremonies and praying would please the gods so no disaster may come upon them.