Theory, theory as to why most other religions have a concept of heaven and a god. You want the Buddhist theory, here it is, you can take it for what it's worth. I'm not saying it's absolutely true, I'm not saying it's false, it's a theory.
According to Buddhism, the Earth cycles, everything spins, expansion and contraction, beginning and end, round and round. All the planets, wherever living beings exist, there's some sort of expansion out of, I don't know, a center thing, and then beings are born in the universe.
The first being who is born is a being named Brahma, neither male nor female. This being has some other names also. As Brahma is the first being who is born, upon realizing only they exist in the whole universe, loneliness arises and desire for others to be born arises. Presto, more are born. Brahma then forms the view that "I created the others." And the new beings believe that since Brahma came first, they were created by Brahma.
Then it evolves so that other realms get born, and because Brahman's way up there in the top heaven realm, there is this basic thought that comes into virtually all the other living beings that Brahma created them. More lower realms manifest with more living beings who wonder who created them. They develop a belief that there must be a creator of all these beings.
Apparently not only is Brahma the first to be born when the universe expands, but due to past good Kamma, Brahma is the last being to die when the universe contracts. Due to Brahma's lifespan being so long, Brahma forms the view that they are an eternal creator God. Unless a Buddha teaches Brahma that their life is not eternal, ignorance will continue to rule even the highest God.
So according to Buddhist philosophy concerning the universe, this is how the concept, of a Creator God in a permanent heaven originated. That's why Christians don't have a concept of Nirvana, as they believe both heaven and the Creator, God are eternal and there is nothing beyond it.
According to the scriptures the Buddha taught that due to heaven being impermanent, there is something higher, which is beyond the realms of birth and death and is called Nirvana or in Pali, Nibbana. Buddhism teaches this higher goal.