photons, gravitons and Many-Parallel-Words are “things-not-needed” and/or “things that cannot exist” and/or “things that could not happen”.
Electromagnetism and gravitation are caused by conserved elementary charges and the time dependent fields propagate with c. Time and space are connected in the Minkowski space. But the stable particles e, p, P and E with their two kinds of elementary charges can physically not be localized in a point of Minkowski space. The positions and velocities of particles are never known exactly.
However, electromagnetic and gravitational waves exist and they propagate with c. There is physically no contradiction between the existence of two invariant elementary charges of particles and the uncertainty of their positions and velocities.