[philh]

That's not quite what it says. It says that there was a time (1200 years ago, in a different language) when he existed with heo, which was female; and then heo morphed to he; and then she was introduced. It doesn't specify whether he was originally masculine or ambiguous.

[thret]

Yes, but it does specify that 'he' was used for both male and female at the time 'she' was introduced in Middle English.