Massive upgrade failure

I inherited a site running under PHP 5.4x, using the Enigma theme version 2.3.1. Since PHP, WordPress and the theme need to be updated, I created a development copy of the site locally, to test under PHP 8. I was able to upgrade the theme, but virtually all of the custom home page layout, for example, is gone. No slider, no “services” — it didn’t even seem to preserve the existing slider and service data. I could add new sliders and services in the Theme Options, but even then they never displayed on the home page.

How can I restore the home page functionality I lost? Do I just need to find another theme and rebuild the site?

The page I need help with: [log in to see the link]