ศาลาชุมนุม

I see this term (when applied to or by human females) as representing something as small, cute and fluffy, that needs looking after.

But I notice that the Chinese character 女 , meaning 'female', is pronounced identically to หนู

Is there any etymology on the origin of the word หนู (when used by or about women) in Thai?

The dictionary has no reference to หนู being a loan word.
It is defined as 1st pp. lower to higher status and 2nd pp. higher to lower. Also an affectionate title given to children หนูแดง หนูน้อย.
It isn't exclusively applied to females.

I am no expert in Thai, but as a Chinese, 女 (girl) is actually pronounced as nǚ (note the umlaut on the letter u), and in this case, the u is pronounced in the same way as the French letter u. However, the word หนู actually has an identical pronunciation as the word 奴, which means 'slave'. In the past, people of lower positions in the ancient Chinese dynasties refer to themselves as 奴才 (pronounced หนู ฉาย). If I am not mistaken, the word หนู is used in contemporary Thai by females of lower positions to elderly or people of higher positions (e.g. manager). So I believe that there should be some connection.