There is also a social norm implied by “Humanity”: to treat other humans in the Way(Dao) of human. (My own translation)
This is a translation from Ancient Chinese.
I am afraid that "in the Way of human" is not a very good phrase, because we usually say "in a humanitarian way". But "humanitarian way" is a fixed term, not appropriate for translating an ancient text. Actually "the way of human" may mean more than what "humanitarian" means. Right?
In China, we too often connected humanitarian with the Red Cross, and the wares it send out(Red Cross is the largest charity organization in China, but it is totally an offical agency).
Later, in TV NEWS and Newspapers you will heard too many times: We have send the humanitarian alms…here it extends to mean any goods for those in urgent need.
I mean I first learnt the Chinese word for "humanitarian", and afterwards, when I learn the English version, my understanding of it is very much influenced by the Chinese word.
Also, the famous doctrine of Heidegger and satre about the humanity is translated into "humanism", not humanitarianism. So I sort of treat "humanitarian" like the word "utilitarian", with its meaning being limited to charity and kindness, compassion.
Best Answer
Both "humane" and "humanity" have connotations to them that suggest proper, ethically upstanding behavior. But, I suspect, you are looking for a way to say "actual human behavior".
To avoid this connotation, you could say that they are treating somoene in "a human way".
The meaning is clear - that the person is acting in a way that a human would - and it avoids the implication that the treatment is "humane" or "with humanity".
I hope this offers some clarification for you, and helps you to better use these terms.
Now that I better understand what you are asking, here's what I would suggest for your quote.
Instead of saying "to treat other humans in the Way(Dao) of human", I would say "to treat otehr humans in the Way(Dao) of a human". or "in the Way(Dao) of human beings".
"Way of Human", while it might poetically be what you mean (The Way Humans Behave) doesn't quite sound right, possibly because it places "human" as a collective. "The Way of a human" or "The way of humans" is a bit more clear.
And technically "The way of humanity" is also correct, because it means exactly what you want it to mean (the way humans act). While "humanity" has a connotation of ethical treatment, it does not have to mean that, and wouldn't necessarily mean that in this context.