Despite downvotes, this, admittedly sarcastic, question makes perfect sense. The name of a "distribution" is the name of the OS. It may not even be a "distribution", like Android. Nobody calls Android "Linux".

Linux is the operating system, the distribution is only a collection of apps running on top of the operating system. Ubuntu does not handle stuff like memory allocation or scheduling.

An operating system is a different concept from a kernel. What you are describing is a kernel, not an operating system.