Humans

You know humans, right? Those diverse chaps who have taken over the planet you live on. Heck, you're probably human. Don't worry, we have humans over in Delta ourselves. They're just as diverse as your humans, so just imagine your version of humans and slide it into Delta, and you have a good depiction.

What more do you want, it's just a human. Use the Wikipedia article|Wikipedia if you need to, it's not that complicated.