Yes what a real blessing Adam's sin was! Not only a ringside seat in heaven for some but all those billions who have had the privilege of dying from nasty painful diseases in order for a spirit ruler to show the world just who is in charge. Jehovah sounds like an insecure bully who wants revenge. None of it adds up.
If you base your life on fairy stories how can you expect to know anything or understand anything? If you can't see that Adam and Eve is a simple creation myth then you still have an awful lot of growing up to do.
And if there was no Adam-- there could be no "second Adam"-- it is very straightforward.
Humans have been on the Earth for 300,000 years. Will Jesus' sacrifice cover our earliest ancestors and how about Neanderthals who interbred with humans--and Homo heidelbergensis and Homo erectus? Where would you draw the line??