Uh, there's a whole world of Open Source out there beyond cloud-related tools and JS libraries.
A lot of the tools and libraries that I use every day are largely written and maintained by a single developer or a small group of developers. Some of these projects started before I was born and will keep on truckin' after I die. This sort of development has its ups and downs, but it's a good life in the long run.
are you very young and do you intend to die soon?
BSD derived works (including parts of MacOS, Windows and GNU/Linux, and numerous embedded devices like routers etc.) are still going strong today.
Most of the code will have been gradually replaced over such a long time, but there are libraries which can trace a lineage that far back. libc and libm come to mind.
Quite a few well known, non-trivial applications still used today were, perhaps surprisingly, first released in the 1970s. Examples: grep, diff, cron, awk, make.