... about the history of the American legal system and why it seems so convoluted today. I didn't get very far, but maybe I will pick up that "hobby" at some point.
The American system is based in the English system, and the English system was implemented and refined over the years primarily by certain key kings.
The original Britons ("original" meaning before the Romans invaded in 43 AD) were driven out of Britain and into today's Wales and Scotland. Various German tribes (collectively referred to as the "Anglo-Saxons") eventually invaded and drove out the Romans around 500 AD. William of Normandy invaded in 1066 and turned the Anglo-Saxons into peasants (he instituted the feudal system England).
Throughout this time, the various kings borrowed their ideas of law from the Romans, but William and his successors also had a separate system for the Anglo-Saxons to deal with disputes between themselves.
This is what turned into what we now call the common law, but civil law (the law decreed by the king) was always a part of the system, as well. The rest of Europe had civil law (from the Romans) but not common law.
Many Americans today think of the American system as one of common law only and these civil laws (mandates from government) are not consistent with common law. But civil law was always a part of the system, as well. The founders didn't really abandon civil law; they just promoted common law as the primary where civil law did not address something.
Unfortunately, governments expand over time, and they have overrun common law principles, which is the main source of the injustices we see today.