>Nitpick, Cash was the “original chain” as the split happened because what became the BCH portion of the network declined to adopt a proposed update
AFAIK adopting segwit is a soft-fork (existing clients will continue to work, only miners need to update), but raising the block limit is a hard-fork (all clients need to update).
Just goes to show it’s not necessarily clear cut what’s considered “original” at every point in time.
Canonically, Bitcoin considers the longest chain in terms of accumulative difficulty (roughly translatable to hash power) the “real one