In Genesis 7:1-24, the literal text is the heart of the "Noah and the Ark" story. Noah and his family go into the ark, and bring animals with them, two by two. A great flood comes, and the world is drowned, but the ark is safe, floating on the flood.
In the internal sense, the flood signifies the destruction of the "Most Ancient Church" - a stage in human development that was - at first - characterized by a simple monotheism, and an innocence, and a high degree of spiritual awareness.
Adam and Eve, in the Garden of Eden, symbolize that initial human spiritual state, before "the fall", when they eat the forbidden fruit of the tree of the knowledge of good and evil. Then, the story of Cain and Abel, and listing the descendants of these people, trace - in the inner meaning - the gradual but pervasive corruption of the spirituality of that church.
In Genesis 7, a flood of water - representing a tide of evil and falsity - destroys that corrupted church. The people of that church effectively destroy their own spiritual lives.
In the Noah story, the Lord preserves the remnants of good and truth that still exist (represented by Noah, his family, and the selected animals), to provide for the beginning of a new church. That's what is meant by the ark and its preservation.