Well, I'll agree some of those characters are static...
Part of the problem--if that's the right word, because I think this part's more a matter of taste than an outright issue, and I don't mind it that much--is that a lot takes place before the book, so a lot of the "dynamic-ness" of the book is lost a bit in the fact that characters have been dynamic...just in the past leading up to this book.
Gatsby and Daisy both change and Gatsby in particular's a very dynamic character, it's just that what we see in the novel is the finished product of years of changing, from the poor farmer's son in Minnesota to the janitor to the assistant to the WWI soldier and officer to the young man in love and finally into the person we see, the man with it all and yet desperately trying to get back what he lost in the past, his girlfriend.
And a lot of that could've been solved by the second part, a criticism *I DO* have with the book--
Nick Carraway as the author and not Gatsby himself.
Nick's not a very engaging narrator, and a lot of the sections where he's just narrating can seem a bit boring if you're not in the full swing of the book...and Nick's not that dynamic, he's meant to be a foil for Gatsby, his Horatio to Gatsby's Hamlet...
But it's HAMLET who gives the great speeches in the play where he's the title character, not Horatio...
So I think the novel might have been more dynamic if it'd been told from Gatsby's point of view, and then at least *he* could tell us--or better yet, the novel could show us--how Gatsby climbed up in life, and what he was thinking, so we could see how the character the main emphasis of the book is on shifts and reacts and changes over time.
But still, I like the book overall (I'll say this--"Heart of Darkness" was a bore fore me, and at least "The Great Gatsby" topped that...HoD is shorter but feels 10x longer...)