I'm not assuming the constants can be changed; axiomatically, they cannot, because they're fundamental constants of the universe. I'm also not assuming that some agent was around to do the tuning. In its basic form 'fine tuning' just means that if one of the values were even slightly different we wouldn't have anything like the universe we see today, including life. The values of the constants appear as if they were tuned.

It's interesting you bring up evolution, because before that theory came about intelligent design was a reasonable assumption in trying to explain how well-adapted organisms seemed to be to their environments. It was as if someone had designed them for their roles! As it turns out the theory of evolution satisfactorily explains why organisms exhibit the appearance of design.

In a similar way the fundamental constants exhibit the appearance of having been precisely set. It's hard to imagine a scientific theory getting 'behind' the constants the way evolution was able to get 'behind' the appearance of organisms...