An idea can be both novel and derivative at the same time.
You create idea B.
It absolutely builds upon idea A, and is in some sense derivative.
But your idea B introduces a lot of new novel concepts on top of idea A that makes it novel.
An idea can absolutely be both novel and derivative at the same time. Most of the best ideas are.
For a hypothetical example, an innovative Linux filesystem requires having the Linux OS, or similar, as a base to operate. In some sense, it is derivative of that prior work. But the new ideas extend the old ideas enough to be novel.
You create idea B.
It absolutely builds upon idea A, and is in some sense derivative.
But your idea B introduces a lot of new novel concepts on top of idea A that makes it novel.
An idea can absolutely be both novel and derivative at the same time. Most of the best ideas are.
For a hypothetical example, an innovative Linux filesystem requires having the Linux OS, or similar, as a base to operate. In some sense, it is derivative of that prior work. But the new ideas extend the old ideas enough to be novel.