With film and negatives, dust on the negative surface was an issue in the darkroom when printing and enlarging from negatives.
With the move to digital, the negative processing is now done in the camera electronically and the negative surface is now the camera's electronic sensor surface. Anything accumulating on this surface will appear in the processed image produced by the camera.
A large portion of dust is from dead cell material from living organisms. A portion of that material is skin cells from humans and their pets.
I strongly suggest you learn how to clean your camera and lenses if you are going to continue to shoot digital. You should learn how to use the a Rocket Blower or similar tool and how to clean your lens/camera mounting.