The answer is: God

Gen 7:16

When exploring the story of Noah's Ark, many tend to visualize the immense structure bobbing atop tumultuous waters or imagine animals lining up two-by-two as they board; however, the act of closing the ark door truly shines a pivotal light on God’s authority and intention in the narrative. As Genesis 7:16 reveals, it isn't Noah or any person who shuts the door, but God Himself. This signal of divine control underlines the serious nature of the flood—it's more than just a survival story; it's an account emphasizing a decisive moment of divine completion.

On a broader scale, this emphasizes an ancient understanding of covenant and protection seen throughout Biblical narratives. The closing of the door signifies both an end and a new beginning. Just as the door to the ark symbolizes separation from a chaotic world, there are other stories like the Passover in Exodus where doors become pivotal. In both instances, the security provided by God's action highlights a mutual relationship—the human components of faith and obedience paired with divine safeguarding.

Fascinatingly, Noah's Ark echoes survival rooted in loyalty and belief, reminding us that sometimes the chosen must retreat from turmoil to forge a path forward into a new era. Additionally, the actual dimensions and design of the ark have often intrigued theologians and scholars, heightening discussions about its construction and the fervor of its worker—Noah became a craftsman due to his faith, setting remarkable precedence!