Reiterating John 3:16, as in its whole meaning…

God says in John 3:16, “For God so loved the WORLD.” Why does God love the world so much? Or the induvial people in it? I find is vaccinating that God loves his people so much. Later in, it says, “That he gave his only son” In this part God sacrificed his only son for his people in the worse way possible death on the cross. So, God not only loves the “World” so much, but he sent his son to save it. After we ruin it by eating of the tree of Good & Evil… But not only did He just sacrifice himself He took the burden of every sin in all existent! After all that, it says, “Whomever believes in him should not perish but have everlasting life” Does this mean we only have to believe in Jesus Christ/God to go to heaven? Also, after all we have done to God, He still loves us and even lets us go to heaven. Like man God is so loving and full of grace it’s remarkable. -Thank you for your time and please help answer the questions I asked or give a comment. God Bless.