There is freedom in not limiting what God can do and who he can use. Luckily the only biblical way to heaven is believing in Jesus Christ, accepting what he did for us on the cross and his resurrection. The rest is for us to decided how we want to live our Christian life, by putting God in box and trying to live according to rules and standards or believe in a miraculous God who can use a child to bring hope to others and paint a picture of heaven. Childlike faith allows us the opportunities to see just what God can do in our lives outside of the what we seem reasonable. Your analogy of the apostles not being able to describe Heaven therefor a child can’t is limiting how God works. Acts 3 speaks of a lame beggar who day after day sat outside of the gates of them temple. You don’t think Jesus ever walked by the lame man or he never had chance to heal him? Or maybe he left the opportunity for another time for just the right moment for God to use Peter to heal the beggar. I like to know my God is bigger and greater than I can imagine and all things are possible with God, even a child being able to experience heaven. As one who has had a miscarriage of twins, it gives me hope and something more to look forward to when I get to heaven, besides seeing my Savior.