The samples show that you can make an app, make a container, and make a service config file, and deploy your app to K8s. Yes, we've been able to do that for some time now.
This thing is supposed to provide a bunch of advanced features for devs to not have to think about. However, the build repo says this:
"While Knative builds are optimized for building, testing, and deploying source code, you are still responsible for developing the corresponding components that: + Retrieve source code from repositories. + Run multiple sequential jobs against a shared filesystem (for example, Install dependencies, Run unit and integration tests). + Build container images. + Push container images to an image registry, or deploy them to a cluster."
"While today, a Knative build does not provide a complete standalone CI/CD solution, it does however, provide a lower-level building block that was purposefully designed to enable integration and utilization in larger systems."
So as a developer you still have to have all the things you had before, but with extra layers of abstraction now, apparently just to support hybrid cloud installations.
The marketing lingo appeals to developers as if it makes all this simple, when in fact it may be more complicated.