God and spirit is spiritual, we are physical. Often God tries to explain our purely spiritual existence by using the physical as illustrations, or sort of shadows of the spiritual, but there is no way for the physical mind to comprehend all the spiritual knows. When we are separated from our physical body at death, no human has followed that happening. Some feel that they have in near death experiences, but we can't be sure.
Here are some scriptures to check. Matt. 27:51, Mark 15:38, and Luke 23:45. These tell of what happened when the spirit left Christ on the cross. Death had never been explained in the OT as going to heaven, but such as asleep. Something profound happened to these who had been asleep when Christ was crucified.
Find the story of the thief that died with Christ on the cross, Jesus told him that he would be in heaven that day.
Christ talks of living after His death in this verse: John_14:28 You have heard Me tell you, 'I am going away and I am coming to you.' If you loved Me, you would have rejoiced that I am going to the Father, because the Father is greater than I.
In the gospel of John, chapter 14, Christ speaks of preparing a place for us in heaven.
Joh_14:2 In my Father's house are many mansions: if it were not so, I would have told you. I go to prepare a place for you.
This is just from the gospels.
I was in the room when my Dad died, to give a sort of first hand experience. I watched two spiritual beings come help him change from our physical world to the spiritual. An hour later when I checked his body, it was simply an empty shell, it had been my Dad only an hour before.