Their origins are in C++, which is what SerenityOS has used. They've never done zig. They explored using Swift as a C++ successor language for the project[1], but seeing the platform support out of Apple was lacking, they gave up and made the bet on Rust[2].

The motivation to use a memory safe language as the alpha approaches sounds more of a longer term bet [3].

[1] https://ladybird.org/newsletter/2024-11-30/#swift-language-a...

[2] https://ladybird.org/posts/adopting-rust/

[3] https://ladybird.org/posts/changing-how-we-develop-ladybird/