The key is that they're statically linked. Even so, you will begin to run into some issues in that time frame.

My last experience trying to deal with ancient Linux binaries on an ARMv5 device running linux 2.4 was pretty abysmal. There were some breaking changes in the mid 2000s, I believe regarding threading? Old executables wanted LinuxThreads while modern linux uses NPTL. Not sure though. Might have just been a userland/libc problem.

Sometimes, even Linux breaks backwards compat to progress.