How about just adding a disclaimer at the top of the readme that the code was written 15 years ago by a much less experienced version of you? You can add that

How about just adding a disclaimer at the top of the readme that the code was written 15 years ago by a much less experienced version of you? You can add that the statute of limitations for this code has (in your humble opinion) expired, so those wishing to judge you might want to look instead at your more recent projects.