Oh my. Do the authors provide any support for this claim? More importantly: what is their affiliation with creationist organizations? Well, back to science.
First, a note about your question. It might seem that you have sketched out two scenarios, but for the biologist, they are equivalent. We know two things: life exists, and life adapts. Yes, the specific circumstances on Earth have made life possible, and subsequently, life has adapted and fine-tuned itself to those circumstances.
Now to answer your question.
I really like the visual representation of the Life Timeline on Wikipedia. 4.1 billion years ago, earliest life appeared on Earth. At that time, all oxygen on the Earth's surface was bound in chemicals like CO2, iron oxide, etc. We are unsure whether the earliest life-forms originiated in the ocean, but we know they ended up there one time or another. The absence of athmosphetic and water-dissolved oxygen of course meant those first life-forms were anaerobes (lived without oxygen). In fact, oxygen was extremely poisonous for our teragrandparents. (We are the ~ 10^12th generation of life.)
So, aquatic life has existed without oxygen, and still exists, whether the solvabily of oxygen is 'perfect' or not.
Another fun fact debunking your chemistry authors statement: water oxygen saturation doesn't reach 100% at all times (linked article provides lots of great information about dissolved oxygen and life, by the way). Lots of life-forms requiring oxygen hence live in a world where the solvability of oxygen is even more than perfect. Furthermore, life exists (but doesn't thrive) in low-oxygen conditions (e.g. pubmed:9510533).