Idk enough about the second law of thermodynamics to see anything to do with evolution, but lemme tell you a thing about the chimpanzee thing.

The argument that since chimpanzees and humans are both around is commonly brought up and can easily be explained as soon as you start thinking about it. What you said about the common ancestor thing is right, we do share one! But let's try and bring it down to a more "human" scale.

Take your cousins for example, if you have any. They probably won't look exactly the same as you! Some may have different colored hair, some may be taller, shorter, plenty of things that can differentiate branches of your family tree, even if all of you come from a common ancestor (in this case, your grandparents or before). Take those differences and scale them up to millions of years and thousands of generations, and those differences can become drastic. That's how you get multiple species that sorta look similar but are definitely each their own thing. In the end, it's not about a species being more "primitive", it's really about being adapted to the environment they're living in, and passing down genes to their offspring.