Baking and eating bread dates back way farther than the bible. Leavened bread arose (pun intended) around the same time as agriculture. Many communities had a central hearth and would bake large loaves of bread.
It is easy to imagine that the bible and Christianity most likely tapped into an existing metaphor.
Cheers, M
I suspect it might come from the Bible story of Jesus breaking too little bread to feed the multitudes.
"While they were eating, Jesus took bread, and when he had given thanks, he broke it and gave it to his disciples, saying, “Take and eat; this is my body.”"