If you haven't broken open a biology textbook and read the chapters on DNA, go ahead and do so.
Atoms have a charge, they naturally collate together, even in space.
Atoms become molecules, compunds etc. These things also have charge, they interact and join together with other molecules dependant on the charges and enviroments.
These joined up elements can form all sorts of things, sugars, acids, water... these again have charges and attrctive-repellant properties.
You can guess where this is going, these things grow based on the enviroment and interactions of the forces.
Acids and sugars are DNA, when interacting with other molecules, they help jin together other molecules, these chains eventually become long enough to become proteins. Proteins are the basic unit of all the bodies tissues.
This process of joining together and interacting are based on laws of physics and influeced by the enviroment.
Taking a step back, the same molecules in the same situation will do the same thing, and other molecules will do different things... To simplify we give reference to
molecule one A
we call molecule two T
molecule three C
and molecule four G
Oh look, in different combinations these molecules form different proteing ACTG ATTT ATGT......
To call this a code, is to misunderstand what just happened ! WE MADE THE CODE to differentiate things we observed.
We can measure the universe with mathmatics, whether it be defining what an angle is, ascribing 360 degrees to a circle and pi. We can then go find mathmatical logical throughout the universe, because we have defned the rules of observation, measurement. It doesn't mean it is a code laid down by someone! That assumption is based on out human perception that CODES and LANGUAGE are made by someone. But WE ascribed the things we saw in the universe, letters, numbers, to better understand it in a perspective we can better understand.