We just use our brains differently now, mostly to find ways that support our default positions, that leave our minds unchallenged and certain.
Challenging yourself is conscious decision. Make choices to challenge yourself, and don't build an echo chamber.
They even did pretty well with computing with the Antikythera mechanism and its predecessors; though, like Babbage, they were limited by the manufacturing technology of the day.
[1] https://www.worldhistory.org/article/1165/ancient-greek-inve...