I agree with you there, but some people do need Adam for their faith, I don’t know why, even most Orthodox Jews don’t find it necessary for Adam to be a real person, and one would think that Genesis would be more important to them than it is to us. But what @swamidass here is doing is great for those who absolutely need Adam and the Original Sin.
Although, “Original Sin” is possible even without Adam, just, in different context. And without the ‘original’ part.
And ‘sin’ part.