Why do objects in an orbit revolve on a certain axis and not 45 degrees out of their axis, or random axis?

Answer 1

If you are asking about man-made objects, the controllers on the ground or pilots of spacecrafts control their attitude in orbit. The object's pitch (nose up or down), yaw (nose left/right), roll (rotation along the orbit) and spin (change in any of the above) can be adjusted as long as there is sufficient control and fuel to expend.

Natural objects (planets, asteroids, etc) may have attitudes randomly determined.

Answer 2

Inertia. To move off their original axis to one 45 deg off kilter, there would have to be some outside energy imparted. Although there is some precession, the earth's tilt rotates.