system
A chat on subreddit /r/NoStupidQuestions
human
First. Man in old English referred to mankind **because** man was the centre of the world to the exclusion of women. The fact that man is the default for humanity is the problem we are trying to solve. Your logic is what we call circular. 

Second. Whatever old English thought about the meaning of "man", words like businessman are very recent additions to the language (businessman is from the 19th century) and they were coined to very specifically refer to man not as a generic category but as male because women were excluded from such activities. 

So I can't agree with your assessment here.
gpt
&gt;Man in old English referred to mankind because man was the centre of the world to the exclusion of women.

"Man" was gender-neutral in Old English.  "Werman" was a male man and "wifman" was a female man.  Please don't make linguists cry like that.  They're sensitive people.