I think differently. For example, if Newton would have perished as a child due to an unfortunate accident, the physics he discovered would have been discovered by someone else. It was just a matter of time. But geopolitical events can turn out very differently due to random flukes, such as the outcome of a battle.

Perhaps you mean Gottfried Wilhelm Leibniz?

We have to admit that the dy/dx notation has proven more useful than f'(x), as we all saw in our first semester of calculus.

Yes, for example.

I would say that individual 'inflection points' might be incredibly rare. IE: maybe only 1 notable event out of 10,000 is like this. But something like this would only have to play out once or twice far back in history before the world we see today would be very different.

Humans were down to 10,000 units at some time.

Maybe some leader consolidated power and convinced the tribe to embark in a journey to move somewhere else where water was more plentiful and food too, we can only imagine that ...had his attempt at convincing the tribe been unsuccesful we would not be here today!

Or maybe the opposite, which is also true...somebody level headed convinced the tribe not to embark in such a journey...to stay, because with so few units it was not the time to make experiments or gambles

Sir Francis Drake raid on the Spanish Armada in 1588 [1]

Colonel Joshua Lawrence Chamberlain, defeating the Confederate charge at Little Round Top in the battle of Gettysburg is arguably the key turning point of the US Civil War - the entire war and subsequent history could easily have turned out entirely differently without Chamberlain's successful order of the 'right wheel forward' maneuver bayonet attack when the 20th Maine was out of ammunition, which held a key ridge in a pivotal battle. [2]

Those are merely the first two that come to mind.

[1] https://en.wikipedia.org/wiki/Spanish_Armada

[2] https://en.wikipedia.org/wiki/Little_Round_Top