while cinnamon was built from gnome 3, it has been completely separated from it for a decade.
both are under active development
I followed Cinnamon’s git closely for years. The commit “Renamed files to Cinnamon” was the last commit to the majority of files over years, despite the fact that Cinnamon had several formal releases in that time. It took literal years for its development to actually get off the ground and not just get some light touches in JavaScript files. The slow start reverberates until this day as you can see with its slow Wayland adoption and OP’s “Mint seems rather outdated” comment. IMO Cinnamon isn’t even the best choice for people who want a Windows7-like workflow. Gnome with Dash to Panel achieves the same with less technological legacy.