My own experiences are fairly unanimous; they evidence that your kind criticism of @Sara H's position may be the thing that is off base. US Christianity may not have an absolute homogeneity regarding original sin but I assert there is an effective homogeneity. When Sara says...
...this absolutely and consistently aligns with what I was taught. It is what I heard from Sister Philip Michael in Catholic school and Reverend Fraley in Methodist VBS. I heard it at Jack Van Impe crusades, at Dranesville bible camp, at Fishnet and at my Baptist church. It was a particularly consistent doctrine and prior to my initiation into LDS doctrine, I hadn't heard the Christian origin story taught otherwise.
To better qualify this discussion I will clarify that I am offering wholly anecdotal experiences and presenting them against what is - objectively & importantly - a well qualified position. That said, it is not your broad attestation about variety within Christian origin teaching that I am debating. I am contending that what Sara presented is especially pervasive in US Christianity. I am fairly certain that if we were to visit 100 churches of the top US Christian denominations, we would hear Sara's original sin story taught in ~all of them.