While indeed the current trend is to abuse copyright via absurd lengths, "modern" copyright law originated much earlier than the USA's founding - in Europe, where it was used as a means to ensure that only words agreeable to the Crown and the Church were distributed, as the technology of the printing press began to spread in the 15th and 16th centuries. Note that the first privileges of monopoly were given to the printers, not the authors; e.g. in Britain the latter were not "protected" by the Law until the Copyright Act of 1709.
Modern patents have a similarly sordid origin; it's not a coincidence that the system arose at a time when the ability to record and distribute information began to grow in tandem with the need for more workers (all potential leaks) to meet product demand, and many patents were to manufacturers and middlemen, not necessarily the inventors. Also, while the granting of patents became systematic around 1450 in Venice, formally publishing the descriptions of patented inventions was not introduced until 1555 by King Henry II of France (and that concept spread very slowly). Basically? Patents were still "viciously protected" trade secrets, it was just that the privilege of breaking your kneecaps for tattling was enforced by the crown.
TL,DR: copyrights and patents originated as self-serving plutocratic legislation; as social and economic systems grew increasingly tangled and interdependent, what appears to be a "modern" system built on mutual respect is the result of enough varied selfish interests pulling taut the legal fabric as to give only the semblance of a level playing field.