Some terms that refer to common people en masse include
• hoi polloi, “The common people; the masses”
• masses, with senses such as “People, especially a large number of people”, “The total population”, and “The lower classes or all but the elite”
• plebs, “The common people, as a whole, or as a group”
As these terms refer to bunches of people rather than individuals, they don't quite address the question as asked. However, one can say an individual is “among the hoi polloi”, “from the masses”, “a pleb”, etc.