In obedience to God’s command, Noah and his sons, together with their wives entered the ark. With them came the animals – representatives of every thing that had the breath of life in them.

Then the LORD shut him in. (v16)

The NT sees the ark as a type of Christ. So Matthew Henry comments:

Those that by faith come into Christ, the ark, shall by the power of God be shut in, and kept as in a strong-hold by the power of God (1 Peter1:5). God put Adam into paradise, but he did not shut him in, and so he threw himself out; but when he put Noah into the ark he shut him in, and so when he brings a soul to Christ he ensures its salvation: it is not in our own keeping, but in the Mediator’s hand.