Basic is a person that is rudimentary in all aspects of their existence. Unoriginal and inept, a tool.
While this is no diss, as several people stated before, even myself, Henz0 is your typical basic person. So is K Steezy, they're both defined by other people's opinion of them. Their self-worth is determined by praise for their ability to ascend within predefined set standards of fashion, subculture and lifestyle. They're not tastemakers, or trendsetters, because their mind simply doesn't think "outside the box". Doesn't make them bad people at all, they're just examples of a basic minded person.