What some other languages do:
https://www.typescriptlang.org/: none
https://elixir-lang.org/: A bunch of different snippets showing different features. Snippet in first screenful is a 7-line actor send + receive
https://golang.org/: print Hello world on stdout
https://www.rust-lang.org: trivial pattern match that prints a greeting in 11 languages
https://www.ruby-lang.org: print Hello world via a bunch of OOP and other features
https://www.python.org/: carousel with a few snippets, showing off some basic constructs. Button to launch a blank REPL-terminal-in-the-browser
https://www.python.org/: another a feature-list-with-snippets, showcasing JS interop, lack of runtime errors with example super-friendly compiler error, a performance graph, and enforcement of semver
https://www.haskell.org/: What I think is a lazy infinite list of primes, plus a blank REPL-in-browser-with-built-in-tutorial-mode and some suggestions to try out
https://kotlinlang.org/: Hello world with explanations of the code. Other tabs have an OO version, an Android activity, and an example of the HTML builder