We know that things like engines don't just spring into existence.
If we assume that this kind of argument, properly thought through and argued for, is successful and if we make no further assumptions about the character of this designer we might be able to conclude some things about it on the available evidence:
First: Engines are very simple, trivially simple, ludicrously simple, in comparison to the human body. I mean the principles of a simple engine can be understood by a teenager without too much trouble. A preteen, with the right kind of tuition, could design and build an engine and although we would be impressed - we wouldn't consider it miraculous. If
anybody built something akin to a human, without relying on pre-existent developmental methods, we would be stunned.
Thus, from the evidence, the designer is always more complex than the design. The designer makes simple things in comparison to it. This is true for every single known designed object so it is very likely true of every single unknown designed object.
Second: There is some purpose behind everything that is designed be it artistic or functional. Therefore - our designer likely gets some aesthetic pleasure from what happens here on earth, or requires earthly activities for some inscrutable end.
Third: A smart human designer can take an existent design and possibly design a better version. This is usually because the original designer was constrained by budget, time, vision or knowledge (or maybe something else). Since we, as designers, can see design faults in living beings (and have so far only been able to produce patches such as 'medicine' and the like), our designer must have been under some constraints and has not been able to return to the project.
Fourth: Since the evidence would strongly suggest that we descended by modification from some universal common ancestor, the designer must have anticipated its creations would eventually discover the methods of science otherwise it wouldn't have bothered to have provided fake evidence that made it look like it was not designed by an agent to those that spend their lives in deep study of the subjects. If the designer had wanted a close look to reveal its handy work it could have done with much greater ease than designing the human body, whole eco systems, and whatever else we decide the designer might have been involved in.
So for some reason, the designer was happy that some of its designed objects would spend thousands of years inferring design, and was also happy that later, some of its designed objects would infer no design after it was able to measure and accrue very accurate evidence. I think perhaps the best conclusion from this evidence is that the designer is some form of 'trickster' being with some maddening cryptic motivations that nobody can understand.
Edited by Modulous, : No reason given.