A few very quick notes. First, we can agree that whether something is called a scientific
law or a scientific
theory has no bearing on its truthfulness; both can be considered facts. Second, the term
macroevolution is used in scientific circles nearly synonymously with
speciation, and
microevolution is used to refer to evolutionary change that isn't related to speciation. When referring to the idea that we're all descended from a common ancestor, you'll want to use the term
common descent, not
macroevolution. It should also be noted that, in addition to the direct observational evidence for microevolution and macroevolution, there is
substantial evidence for common descent. Third, I agree it would be absurd to expect modern DNA to form suddenly on its own from natural processes. DNA, like complicated life, likely evolved from more primitive molecules. While we don't know the exact process by which DNA and its precursors formed, we do know numerous ways in which precursors to DNA could have formed, and once we have self-replicating precursors to DNA, evolution can run its course to today. I can talk more about ways in which DNA precursors might have formed, but it's pretty dry for a gaming forum. Lastly, even if we disproved evolution and/or had no explanation for how DNA came into being, absence of an explanation is never evidence for another explanation.
Might the universe have had a cause? Sure. Is there any reason to think the universe is required to have had a cause? Not really. If causality is a property of the universe, it's a bit silly to talk about causality requiring a cause. It's also possible the universe in some form has always existed. In essence, there's no excuse for a hypothetical god not requiring a cause that couldn't also be applied to the universe. In fact, it might be fair to say the universe has always existed when time as we know it exists a finite amount backwards, but that's a matter of semantics.
If the universe did have a cause, there's no reason to think it wasn't a natural cause. Perhaps the natural cause to the universe has always existed in some form. Perhaps the cause is atemporal. Perhaps it's a causal loop of the universe in a future state causing the universe in a past state (e.g. something natural, or Stewie Griffin's time pad exploding and causing the Big Bang). We just don't know, and absence of an explanation is never a reason to believe another explanation.