Many of the things which we are assuming might not be true. We are liable to make mistakes as humans. We make mistakes because we do not know everything. And God is not obliged in any way to reveal everything to us. He is God and he is supreme. He does as he pleases. Whatever He wants us to know, that is what he tells us. The Bible says that the secret things belong unto God. It is what is revealed that is for us and our children.
We have read in the Bible about Enoch and Elijah who were taken into heaven. We also heard from the story Jesus told us about the rich man and Lazarus that there is a place called the Bosom of Abraham. All of these are forms of heaven. But it does appear that the Bosom of Abraham and the heavens where Enoch and Elijah were taken to are different from the throne of God. The Bible says heaven is the throne of God.
The Lord Jesus Christ gave us a conclusion over whether there is any man in heaven when he told us that no man has ever ascended into heaven except the one who descended from there. And we know that no man has descended from heaven except Jesus Christ. So, it shows that there is no human in the highest heaven.
Paul the apostle talked about the third heaven. This suggests that there are levels of heaven.