The interactions that go to make and change the
weather conditions around the globe are so complex
that there is an entire field of study (meteorology)
devoted to it, and yet weather changes still cannot be
reliably predicted.
Since the global 'weather system' is so complex, does this
mean that someone designed it?
A hammer is incredibly simple in both construction and
design.
Does this simplicity mean that the hammer was not designed?
I am walking in a field and I come across a rounded stone and a
long stick on the ground. Do I immediately say that someone has
been here and dropped their lever?
I do not see how complexity can be used as a design criterion if
some designs are simple. In fact most design refinement is a
matter of simplifying things to improve efficiency. If anything
high levels of complexity would tend to indicate low levels
of design effort.