No but it does influence whether they’re likely to stick around. If an environment is more complex, for example by having multiple potential sources of food, then that fact provides opportunity for organisms to adapt to those novel sources of food.
If the environment contains only one type of sugar, there’s no selection to retain mutant enzymes that can act on other types(or their upregulation), since these sugars don’t exist. So while such mutants might arise from time to time, they’re likely just lost again.
Yes if things had been a little bit different, then something else than what we currently see in the biosphere might have been favored instead. In that sense, what evolves is due to some combination of the exact environmental circumstances at the time, and the particular sets of mutations that happened to occur instead of others. That’s evolution for you. “Fine-tune” some environmental parameter and/or the initial conditions to something else and you might get some other bricolage adaptation that looks unlikely after the fact.
You seem to have misunderstood what @nwrickert was trying to explain. He wasn’t saying what “drives evolution”. He was saying what drives the evolution of innovation.
And I think you’re getting molecular and physiological/anatomical evolution mixed up. I see this misconception about the neutral theory of molecular evolution a lot among ID proponents and creationists.
While it is true that most mutations (at the molecular level) are neutral or very nearly so, it doesn’t follow that natural selection doesn’t play a large role in shaping the kinds of macroscopic, anatomical adaptations we see in ourselves and the ecosystem around us.
Most mutations don’t contribute to the shape of your limbs(and among those that do, they probably mostly have very small effects), but you can be sure the shape of your limbs was significantly affected by selection. That is to say that, among all the mutations that occurred historically in the primate lineage, the proportion of them (either alone or in combination) that did significantly affect the shapes and proportions of our limbs were likely to have had considerable selective consequences.