Some explanation from Product Expert (Google Search)

> Regarding the search for [white american inventors], the results would reflect the way the images are labelled. Check the image descriptions and you will find that the image results all contain some of the words you searched for. Maybe the webmasters who label images of inventors have no interest in the colour of the inventor's skin!

https://support.google.com/websearch/forum/AAAAgtjJeM4xP2ts6...