browsing tumblr, and while I appreciate the sentiment, I think somebody REALLY over-thought this. I'm trying not to think about what the spread-legged dress-wearing person is meant to imply. From my experience, sometimes well meaning cis people think that trans inclusion is way more complicated than it is when all you need to do is say "All Gender Restroom" and the text below, you don't need the symbols, but as I said, I appreciate the sentiment. :)
BUT, because I'm me, I can't help but look at it and try to imagine what those symbols could mean so... here are my guesses (from left to right, top row, then bottom row)!
"Superheroes are allowed" "Non-powered people are allowed" "Heroic superheroes who need to pose are allowed" "Superheroes can use the stalls to change in and out of their costumes" "Doing the Hokey Pokey is allowed" "Both slow and fast wheelchair users are allowed"
What's yours? :D