Oh so you've decided the dust represents something, rather than God using it to create us. So you have decided you can take the scripture figuratively on man's authority.
You've also decided the creation of Eve is figurative rather than an actual rib. You don't draw this conclusion from scripture, this is a conclusion from man's authority and you have decided to read the scripture figuratively to match it.
Well I'll answer your question, but you have not acknowledge or attempted to answer why complex plant life existed before life in the ocean, when this is completely incompatible with the evolutionary theory you subscribe to.
So answer me that, and don't ignore it because you can't talk your way out of it, even with false science.
So if I understand correctly you are asking me why creatures began in the ocean, and the significance of this? Because God started life in the ocean in his decision. Now I won't proclaim to know the mind of God or explain his actions on my own authority. I can make a guess though. Ocean animals live in the ocean, birds fly above the earth, land animals live on land. Humans live on land. It was a perfect progression toward our "living" domain. This is my guess, I'm not claiming it on my own authority or man's, but I do know it occurred in the order described in The Bible on God's authority.
Do you subscribe to the whale evolution? Why does the Bible state God created Whales in the ocean before land animals, yet you subscribe to a theory that states the whale was first a land animal?
There are two possibilities for these incompatible beliefs. Either you don't subscribe to the whale evolutionary chain, or you have deceived yourself into believing The Bible wasn't talking about "those whales" when it literally said whales. You can reject evolution on this matter or you can reject The Bible by forcing figurative or symbolic reading of this literal verse. Which master do you serve?