> But I would really appreciate it if anyone else has more thoughts about how to filter out images that do not contain people :-)

Google allows image searches to be filtered by is/isn't a face. I think you could tap into that knowledge, although it isn't immediately clear what the route would be.

Here's a detailed rundown of the more obscure google search paramters: https://stenevang.wordpress.com/2013/02/22/google-search-url...

The relevant one to your interest is "tbs=itp:face".