When they see a living thing, don't most people assume it has at least one parent?
For modern, complex life we do assume that it came about through biological reproduction. We do not assume that it came about through magical poofing by a supernatural deity because there is no evidence that this ever happens, nor any evidence that there is a supernatural deity capable of magical poofing.
Simple common sense will answer most questions that science struggles with.
"We don't understand it, therefore God did it" is not common sense.