Darwin is definitely the best option here.

I find the constant flux kind of amusing and appropriate (humans are self-conscious animals who can't even agree on what they look like), but I guess it can be a source of acrimony. Two suggestions:

1) We implement a feature that allows people who curate a taxon to prevent changes to the taxon photos by non-curators (Wikipedia does something like this for their Homo sapiens page)

2) Someone (one of you?) makes a 4- or 9-image square collage of public domain human photos that achieves the goals of a) honoring the greatest contributors to our understanding of and protection of nature (e.g. Darwin, Carson) and b) depicting the diversity of human forms, posts that image to Flickr / Wikimedia, and we can set that as the default.

It looks like this has happened again (Apr 2019), with both Darwin and Linnaeus being removed. I've re-added the two.

For what it's worth, the issue of taxon photos has also been occurring on and off throughout Hymenoptera, often with misidentified Flickr imports.

I set the default taxon photo for human to a photo of Gladys West. She is a mathematician who worked on the math and science underpinning GPS, which is a huge part of what makes iNaturalist work.

We have made it so only staff can edit the photos for certain taxa, and have applied this to Homo sapiens and taxa with Linnean ranks (KPCOFGS ranks, so not things like subfamily) that contain it in an effort to a) stop people from constantly changing the photo of Homo sapiens, and b) avoid offending people in cases where iNat's automated suggestions may suggest a taxon that contains Homo sapiens when attempting to identify an image of a human.

The photos we've chosen are composites of public domain (or similarly unrestricted) images. You can find links to originals by viewing the details page for individual photos.