I'll contend with your second point as time is limited, but my brain even more so. I'll let Motar handle your first point.
Forget Adam, Eve & the snake. Is there sin in the world - murder, hate, lying, lack of compassion, etc. etc.? Why are we humans not glorious works of compassion and peace? Where did the "evil" come from?
As for Christ's atoning sacrfice - it is most certainly brutal and you think more rightly of it than some I sit next to in the pews on Sunday. It is no small matter to be glossed over. What kind of thing is this that we are to believe? In regards to your comments - "believe the right things & follow the proper rituals" - there is only one thing to believe. No rituals required, actually riutal is in opposition to faith. So, here is the one thing to believe - I am a sinner. God Hates Sin. The penalty according to God for Sin is death. Jesus died in our place. Place your faith in Jesus - believe rightly on Him in this regard and your sins are not counted against you.
Absolutely Crazy! How can anyone believe it? Well, you can't. Yet, God provides a way for belief. He sends the Holy Spirit to convince because how else will anyone be able to believe. Now, don't say to yourself. "Well then, I am free and clear. The Holy Spirit hasn't convinced me so why bother". Maybe instead, go after God and genuinely ask him about it. And, though you may imagine the Bible to be fable, what's the harm in reading a book or two. Read John especially chapters 15 - 18. Seek and you shall find. Seek: to attempt and desire to find something. Actively seek even though it goes against all your common sense, reason and judgement.
Indeed if one has common sense, reason and judgement they know the perils of unmanned battlements and they would not trade what they righteously won for figments of faith. Like's been said a billion times before, those who shelter under faith are soon frozen dog treats. Daveiticus 7:12