Well, to be fair, a lot of Einstein’s work was based off the work of others, it’s just that he managed to finally fuse a bunch of theories and ideas together into working equations. ‘Shoulders of Giants’, and such (though that’s Newton).
Actually they had some electromechanical computers those days, but they were pretty primative.
On that subject - if there weren’t any transistors, we would be doing calculations on these little babies:
That is a Curta calculator. Developed by a death camp inmate during WW2, it’s a marvellously compact totally mechanical calculation device, capable of some stunningly complex functions. Still available for sale, too, though I can’t justify buying one.