The apostles were a very diverse group. John the son of Zebedee is usually thought to have been quite young; Bartholomew is often depicted in religious art as rather old. There were fishermen like Simon and Andrew and a toll collector like Matthew—and if the other Simon was called “the Zealot” because of his politics, then among the Twelve we find both a Roman collaborator and a revolutionary!
Some of the apostles may have been relatives of Jesus, or at least that is how they are sometimes depicted in early tradition. According to Hegesippus, Alphaeus (also known as Clopas) was Jesus’ paternal uncle, which makes Alphaeus’s sons James and Judas (and possibly Simon?) Jesus’ cousins. Another theory—and keep in mind we’re dealing in speculation here—is that Salome, the mother of the sons of Zebedee was a cousin of the Virgin Mary. At any rate, other disciples had never heard of Jesus before, and yet they followed him. Philip had a Greek name and apparently a ready rapport with some Greeks who came to see Jesus (Jn 12:20-21), but it is safe to assume not all of the apostles were so cosmopolitan. Some of the Twelve had been disciples of John the Baptist; others may not have had much spiritual background at all. If this bunch got together for any other reason, do you imagine they would find much to talk about?
Whoever they were, Jesus called them. We are never told what it was about them that caught Jesus’ attention. It was probably not their intelligence, their upbringing, or their natural abilities. More likely it was an attitude of their hearts: a hunger for God or a teachable spirit.
Jesus is still calling people of every sort to be with him and to go forth in his name. If church history is any indication, he is still uninterested in producing cookie-cutter disciples who all look and think alike. Apparently, it is good for the kingdom for a whole lot of people from many different backgrounds to find their unity in Christ alone.