By default, modules in the module-path that are not explicitly required are not loaded. The correct fix, that avoids using --class-path, is to add requires statements for the LWJGL natives in the application's module-info.java, for example:
requires org.lwjgl.natives;
requires org.lwjgl.glfw.natives;
requires org.lwjgl.opengl.natives;
Note that org.lwjgl.natives transitively requires org.lwjgl, so you don't need to specify requires statements for both.
Alternatively, you could use --add-modules ALL-MODULE-PATH to force loading of all modules present in the module path, even if they are not explicitly required by your application.