Well how do archeologists know that Neanderthals designed their own tools? Nobody has ever seen a neanderthal creating anything, so how do archeologist know?...
The answer is simple, one can infer design by just looking at the pattern
Let's turn it around a bit. Suppose we have something that looks like a tool and ask if the local Neanderthals could have designed it. How could we answer such a question?
Well, among other things, we can do studies, based on the bones, of range of movements, forces available, etc and we if the artifacts we see could have been formed by the allowed motions.
But, before we even consider whether the artifact was designed at all, we would first look into what sorts of artifacts occur naturally. And, while this isn't as big of a deal for Neanderthal artifacts, it *is* a big deal for earlier ancestors.
So, we find a crushed antelope skull, or we find a rock that might have been chiseled. How do we determine if the skull was intentionally crushed and if the rock was intentionally formed?
And the answer is that we *first* determine what sorts of skull crushing happens naturally (say, after death, or by wild animals eating) and what sorts of marks appear in *unintentional* modification of rocks (falling from a cliff, for example). We then do a careful analysis comparing those that are formed 'accidentally' and those that were formed 'purposefully'. Only then, can we take an artifact and say it was more likely to be intentionally formed or not.
In the case of fine tuning, however, we don't have anything to compare to. We don't have any way to play around and see what constants come about by 'natural' processes. And, in fact, we don't even know whether it is *possible* for the constants to be any other value.
So, in regards to fine tuning, we are in the situation where we see an intriguing rock, but have no way at all to see what sorts of rocks form naturally, or even if there are other ways for the rock to be formed.
If you want to make a case for fine tuning, the *first* step is to show that it is possible for the constants to be different than they are. If you manage to do that, we can *then* look at the dynamics of those changes and see what drives such changes. And only after that can we even address the question of whether an intelligence directed the changes or not.