It's impossible to know with certainty who the first person to believe in and spread the concept of God was. The origins of religious belief are shrouded in prehistory, long before the development of writing. Here's what we can say:
* Prehistoric evidence: Archaeological evidence suggests that humans have engaged in ritualistic behaviors and held beliefs about the supernatural for tens of thousands of years. This includes cave paintings, burial rituals, and the creation of symbolic objects. However, we can't definitively interpret these as evidence of a belief in a specific "God" concept. They could represent ancestor worship, animism, or other forms of spiritual belief.
* Gradual development: The concept of God likely evolved gradually over time. Early humans may have started with animistic beliefs, where spirits were thought to inhabit natural objects and phenomena. Over time, these beliefs may have developed into more complex systems of polytheism (belief in multiple gods) and, eventually, monotheism (belief in one God).
* No single individual: It's unlikely that a single individual invented the concept of God. Instead, it was probably a collective and gradual process, with ideas and beliefs being shared, modified, and passed down through generations.
In conclusion, while we can trace the development of religious ideas through archaeological and historical records, the question of who first believed in and spread the concept of God is ultimately unanswerable.