I have to concede that I still talk in this now outmoded manner. I have to make a conscious effort to switch to modern gender neutral language (eg. they) when speaking or writing to anyone outside my family and friends.

> English language changed to expunge the ambiguity.

I think it's more accurate to say it adopted different ambiguities. The use of 'they' can create ambiguities of number, and just switching between he/she leaves the same ambiguity (is the gendering intentional or not?) albeit in a gender balanced way.

As a side-note, 'he' was used to refer to people, who could be regarded as interchangeable (man or woman) and 'she' was reserved for 'uniquely individual' things, which is why countries and ships (as two examples) are referred to as such. At least, this was may understanding when growing up and I've never lost this habit.