One way to respond to certain design arguments, including both fine-tuning arguments and arguments from apparent biological design, is to make use of a multiple universe (MU) hypothesis. If there are enough universes (say, infinitely many), and there is the right kind of latitude in the random parameters, it is unsurprising that there be a world exhibiting just about kind of complexity you like, including intelligent life. And there is no further puzzle about why our universe exhibits this complexity, because there is a selection effect—only universes that have observers can be observed.
One might think that MU and Design hypotheses cannot be distinguished. That's why some design arguments are formulated with a disjunctive conclusion. But they can be distinguished: they have distinct predictions. The MU hypothesis basically says that we should expect to see just enough complexity and tuning needed to produce observers. The Design hypothesis makes it moderately probable that there would be more complexity and tuning because of the value of living beings that are non-observers. More genearlly, the difference is that the MU hypothesis involves only a tropism towards intelligence, while the Design hypothesis involves a tropism towards the instantiation of values. So in theory the two hypotheses could be distinguished.