Unlike art, there are strict definitions of "best things" in practical programming: Readability, speed, ease of use (in final product), and more stuff but I don't know. And source code, is usually just duplications of source code in the past that achieve those things, group into a single project. So if every stolen code was illegal, then bigger than 95% of programmers are criminals

There are competitions about the most unique source code (obfuscated C code), but most of them are just for shits and giggles, not to put in practice at all

TLDR: Programming is mainly putting all the good things together, and depend on the time, there is only one best thing, for different categories: Readability, speed,... . Programming doesn't aim for code originality, but there are competitions about it for shits and giggles