MacOS access to PowerPC apps on Intel hardware was actually discontinued when Mac OS X 10.7 Lion was released about twelve years ago. Since then, eleven major upgrades to macOS have been released.
If you have been using those apps ever since then, my friend, you have been computing on borrowed time!
And 3 1/2 years ago macOS dropped support for 32-bit apps as 64-bit coding has become the norm. These changes are made for the sake of faster computing and forward progress of the tech. Steve Jobs, in fact, was heading Apple when the macOS became UNIX-based and the switch was made from PPC to Intel silicon. We've all been treated the same by Apple for decades. 😉
To start, you could continue to use your obsolete hardware and software if for no other reason than to access those legacy files.
Or you might have a look at these documents from Claris to learn how to move forward:
How do I open FileMaker Pro files created in earlier versions? – support.claris.com
Converting older FileMaker Pro files to the .fmp file format – support.claris