Saying Goodbye to My 1 Year Megabuild

I've been working on an Ancient Greek City map for over a year using Axiom on 1.21.1, also running shaders, distant horizons, and sodium. I decided to update all my tools and minecraft to 1.21.10 but made the mistake of not backing up my world. When I loaded back in, new terrain generated over the entire city, R.I.P. I put so much time and effort into that city that I'd rather start fresh than to try and rebuild everything. I made this 1408×1408 world in WorldPainter (first time using it) and plan to go for a more Medieval European style build with about 2-3 different kingdoms. Any recommendations are welcome, I'm excited to get this started.