Comparison

There exist many tools that try and make working with webpack easier:

create-react-app – a great and powerful tool. I personally tend not to use, because I find it slightly big and intimidating with a large codebase, it's overly React specific and brings in opinionated tools such as jest testing framework. But it's a very comprehensive tool with great documentation, so keep using it if it works for you!
pwa-cli – very similar to what jetpack is trying to do. Has a neat plugin system for extending its functionality beyond what the core provides. Why jetpack and not pwa-cli? Not sure, you'll have to try both and see what you prefer.

There are also alternatives to webpack:

Parcel is making 🌊. Let's see what version 2.0 brings to the table. It has very similar goals to that of jetpack's – most things should just work and be convenient without configuration.
Browserify – probably still has a hard core fan base ;) with dev servers similar to jetpack, e.g. budo and bankai to mention a couple.

There also exist higher level frameworks for certain use cases:

Next.js - use this when you need server side rendering. Server side rendering can be tricky to wrap your head around and so when you just want an Single Page Application – jetpack might be a better choice.
Gatsby.js - use this when you're building a web app that can be exported to a bunch of html files – it's a great fit for websites. For richer, interactive web applications, jetpack might just be a simpler choice.

In general, where jetpack tries to be different is:

make it possible to run globally anywhere on your machine, just like you can run node ~/Desktop/test.js
have good workflow for simultaneously developing the client and the server
make sure that if no configuration is touched, the application is bundled in the best possible way for production
serve the SPA use case well (as opposed to SSR or SSG)

Bonus

Because jetpack avoids anything too fancy, a lot of the time your app might already work with jetpack out of the box. For example, this works:

$ npx create-react-app my-app
$ cd my-app
$ jetpack