You should use @wordpress/scripts so you can profit from modern JavaScript language features and JSX and transpile it to browser-compatible code. It’s really not complicated to use.
Just install it via npm install @wordpress/scripts --save
and than you can transpile your source file like this wp-scripts build src/myguten.js.js --output--path=js
.
It’s not only modern language features but versioning and dependency management that comes with it too.