The theological idea of Heaven and Hell is tighly connected to the ancient idea of Order and Chaos. Heaven is the ideal order where creation is manifested while Hell is the ideal chaos where destruction is manifested. I don't want to go deep but that is the idea. I believe, and I think it's true, that you can experience a bit of heaven when you are sorrounded by your family, loved ones, and friends, whom you truly love and care, who genuinely love and care for you. On the other hand, it's not that difficult to experience hell. Some experienced it in a daily basis. During the peak of pandemic, any person with some sense would recognized it as the hellish moments of their lives when people close to them are dying one after another. What I am saying is that there is no need for mankind to be perfect (or death even) to experience either one. There is a bit of truth when religion claimed that you could go to heaven when you do good and every person is encouraged to do specifically that because the alternative is the place where no sane person would want to. It's not surprising if it doesn't make sense or even exist to you or anyone who embraces the secular worldview since the concept is outside the material/natural domain. As matter and physical reality is best explained by Science and Physics, Heaven and Hell is a metaphysical reality best explained by Theology and Philosophy.