I'm currently working on an old program written in C that consists of a shared library and some utilities. The library is built by first building every subproject as a static c library and then linking those together in a shared library.
The layout of the project is very similar to the project in this question.
Previously I built my C programs by linking every object build together. What is the benefit of using static archives instead of object files in this case?
There is no particular benefit, but building multiple archive libraries which are later linked into a single binary or shared library can make
Makefiles easier to write. However, see "Recursive Make Considered Harmful".