Over 50 famous and maybe not as famous people of the GLBTQ+ community are in the pages of the book Queer Heroes: Meet 53 LGBTQ Heroes From Past and Present! While I did not count, I would guess at least half or more of the people mentioned are not mainstream (but known in certain circles) or might be the first time the reader (and most) have heard of/about them. Of course there were several more well known (Freddie Mercury, Ellen DeGeneres, David Bowie (who never identified himself but called himself gay, bisexual and a closeted heterosexual), Billie Jean King) as well.
They start with Freddie which I thought (before I had read the paragraphs about him) was odd. Then the author, Arabelle Sicardi, said that Freddie sang about “breaking free.” And that is the theme of the book. How the people they covered, broke free. Some did it by being themselves (Jazz Jennings), some did it by being in the public eye as the first openly gay female Icelandic prime minister (Jóhanna Sigurðardóttir). Some did it because if they didn’t, others would be imprisoned and/or killed because it was illegal to be openly gay in their countries (more than one person was here). And others did it by protesting or setting up programs to help everyone from AIDS patients to gay refugees. Some people mentioned (such as Da Vinci ) are giving the argument they probably were queer, but also there is not “solid” proof. This was an interesting inclusion, but also important. There are literal princes, movie stars, dancers, singers, politicians, athletes, and some who were young, like Emma Gonzalez (a high school senior in 2018 and a surviving of a school shooting and is queer) when they first spoke out. 
While the highlights of their lives are well done, only the positive pieces and their influences are included. (Josephine Baker had issues with her adopted children that are not mentioned, but the fact she had adopted them was.) But overall, things are well done, well written and covers several genres. There were a few bumps for me with the illustrations by Sarah Tanat-Jones, for me. The not abstract, but not as realistic either, artwork can be a bit “off putting” for some people and the almost caricature 
look took away from the theme for me.
There are extras which include a glossary, an introduction that talks about things like taking the work “queer” back, and sources and resources. However, there is also a disclaimer at the very end that the
author/illustrator/publisher do not endorse the resources or guarantee them.