Again, you are not fooling anyone when you insinuate things and then act offended when someone actually responds to the insinuations. [EDITED to fix a typo]

The past is not outside the domain of scientific knowledge. (Unless you refuse to call something "knowledge" unless it is known absolutely for certain, in which case the situation is much simpler: there is no such thing as knowledge, scientific or otherwise.)

The way science works is: you have a bunch of observations, you come up with theories that attempt to explain them, you try hard to refute those theories by thinking of tests/observations/... that will give different results depending on what theory (if any) is right, and you try hard to look for alternative theories to explain the observations, and the situation you hope for -- which happens very frequently -- is that you have one not-too-complicated theory whose predictions match the observations well, and that despite extensive efforts no one has found a theory that does as well without being much more complicated (e.g., by "baking in" the actual observed results), and then that theory is the one you provisionally treat as "true" until that situation stops obtaining (e.g. because someone found a better theory, or it fails to account for new observations).

(yesyesyes, this is a simplified account, but I claim it captures the essence of how science works)

You will notice that nothing in that paragraph forbids those theories to say things about the past.

Which is just as well, because the very most primitive scientific activity possible, namely making and reporting a single observation, is necessarily about the past. Suppose I measure the temperature of a liquid by immersing a digital temperature probe in it and looking at the output. It takes a bit of time for the sensor in the probe to equilibrate with the liquid around it. It takes a bit of time for the electronics in the probe to do their thing. It takes a bit of time for the light from the display to reach my eyes. It takes a bit of time for my brain to process that and turn it into an actual number. By the time I write "115.2 degrees C" in my notebook, the actual liquid-being-at-that-temperature is several seconds in the past.

But I'm still happy writing the number down, because by far the most likely explanation for my current state of "thinking I have just read the display as saying 115.2 degrees C" is that a few seconds ago the temperature of the liquid was about 115.2 degrees C.

Of course it's always possible that I've suffered some strange brain aberration, or that the probe is malfunctioning, or that an angel reached down and interfered with the experiment. Or that some currently-unknown physical phenomenon invalidates the way the temperature probe works, for this particular liquid in this particular situation. Everything in science is provisional. But the fact that something's in the past doesn't in itself make it more provisional. And, while those exotic alternative scenarios are possible, they aren't likely: strange brain aberrations are thankfully rare, lab equipment usually either works or fails in obvious ways, miracles are rare if they ever happen at all. So we generally do OK to ignore those scenarios until plenty of actual evidence for them turns up.

So, anyway, what of your example? In any actually plausible version of the scenario where one human being makes a statue that's later seen by another, that other human being is going to find plenty of evidence of other intelligent beings who might have made it. (E.g., to be excessively literal about how you set up the scenario, if I observe that statue then I am going to be aware of having seen many many other statues before all of which I have good reason to think were made by people.)

So if you want hypothetical-me not to think it plausible that the statue was made by an intelligent being, even though in fact you made it, you're going to have to go to great lengths to erase from the world -- or at least the portion of it that I get to see -- all evidence of other people who might have made the statue. And it's going to have to be a hypothetical-me that lacks all the real-world knowledge I have involving other people. And, well, if hypothetical-me is looking at a world from which all evidence of other intelligent beings, apart from that statue itself, has been carefully erased, then I am not sure it's much of a gotcha to say "aha, your so-called scientific approach will never discover the intelligent designer here!". If you falsify the evidence competently enough, you can indeed get someone to believe something false; how exactly is that supposed to indicate that they're doing it wrong?