Are you advocating that someone standing next to LHO took the shot?
No, I’m advocating that Brennan didn’t see a rifle being fired. This is a nonsensical question anyway since you don’t know where Oswald was standing at the time.
Thomas Canning's Trajectory Analysis places the shots from the window where Brennan witnessed the man taking the shot.
Those “trajectory analyses” are contrived to get a desired result. If you preassume when the shots occurred, how people were positioned, and exactly where the conflicting locations and angles of the wounds were, you can get the result you want. At least for the back wound. The head shot…not so much.