I, personally, role-play humans - practically - twenty-four-seven; I have more than eighteen of them.
Now, I don't use the "human" markings that others would use; I use the markings that I find attractive and pretty to me - I also use any color, too.
Take Lucas ans Wolfie (Wolfie being my avatar and Lucas being my siggy). Believe it or not, they're both humans. Wolfie has the default "Bubbles" for the body, "SpottedHyena" for the face, and the "HighRing" for her tail. Lucas has MM (can't remember which ones, though), and they both don't look like humans, but I role-play as them.
And, TwistedLizard, Wolfie doesn't know how to use a gun - nor does she have powers, she's a normal being. And Lucas is a SnK OC of mine, he knows how to use his 3DMG and his only "power" is him being a titanshifter (though, he's currently not aware of it).
They are both white - though Lucas is technically half-Spanish - because I'm white and I mainly see white people - I'm not even trying to be racist, it's just common for me to see. I know that role-playing tries to make new experiences with you, but you can't just experience it without it being physically in front of you.
Maybe it's just me, though.
-Wolfie
Hey, Wolfie! *Waving*
But, i have to agree with most of Wolfie here.
Along with dragons, Humans are also something I commonly roleplay. I personally have three myself, one of them being a WIP. I'll touch dragons in another thread, of course, but for now onto the main subject!
I have Rosalva Arce, Yeva Monore, and Estelle Sonnen. Each of them has a marking set that, not only resembles hair or clothing color, but also personality.
For instance, Rosalva has Corgi for body and Raccoon for head (Both MM3 markings). Corgi has a soft, subtle feeling to it, representing a calm outlook on the world and a kind interior. Raccoon represents the cold and uncaring exterior put up around her in two ways. It's actually quite jagged, not fading into wisps like say the German Shepard face marking. The raccoon 'mask' is, of course, that uncaring mask. It can also be used to represent her past, which she is skillful in keeping hidden. Her tail markings I don't remember, but I think they represented her rank within the Shatterdome. Rosy is a Ranger, or Jaeger Pilot. She isn't called into action as often as you'd think, and outside of the Drift the only 'power' she has is the leftover link to her partner from the Drift itself, A.K.A. Ghost-Drifting.
Yeva has no powers, unless you count excellent tree-climbing as one. Then again, she has an oak in her backyard she's used to climbing.
Estelle is the WIP, and is an SnK OC. The only thing I think she knows how to do is use her 3DMG.
As with Wolfie, I'm not racist, just not used to roleplaying people of other colors (Rosy has spanish bloodlines and Yeva has French and Russian, I believe). It all depends on the person's abilities and experience with what and/or who they roleplay, anyways.