I also find that people are deep wells of content. There can be definite limitations to what you can say about a product or how you can describe a service. But the people behind those products and services can be never-ending sources of stories and insights.
And despite the tendency to pigeonhole whole swaths of people into broad, generic categories, in reality there are an infinite number of variations with people. And to me that makes for interesting reading. Two guitarists who play the same style of music -- hell, two guitarists in the same band -- will have differences in their approach, their background, and what they bring to the songs.
From my perspective, the best thing you can do when creating social media content is focus on the people.