Is the feeding of the five thousand the only time we read of eating together in the New Testament? Of course not. The Lord’s Supper, the Eucharist, was most likely an actual communal meal - a symbol yes, but an actual shared meal, the anchor of the early Christian community. John Dominic Crossan talks about the Lord’s Supper in his book “The Birth of Christianity”:
“The Common meal Tradition may look to a Last Supper in the past, to a communal meal in the present, or to a messianic banquet in the future - or, quite validly, to all of those at the same time. But it can never get away from this: It is in food and drink offered equally to everyone that the presence of God and Jesus is found. But food and drink are the material bases of life, so the Lord’s Supper is political criticism and economic challenge as well as sacred rite and liturgical worship. It may be all right to reduce it from a full eat-and-drink meal to a token nibble-and-sip meal as long as it still symbolizes that same reality - namely: Christians claim that God and Jesus are peculiarly and especially present when food and drink are shared equally among all.”
So is the "feeding of the five thousand" story related to the common meal tradition in early Christianity? Who knows? It’s an interesting, albeit speculative, thought.