Discharges of a 1911 type pistol from being dropped on the muzzle were almost unknown until the advent of full length guide rods. In the original design, the slide can move back against the recoil spring, cushioning the blow. It is still not absolutely safe, but the FLGR makes it very much less safe since there is no cushioning of the blow at all.
In other respects, the 1911 is pretty safe. A pistol with the hammer down cannot fire if dropped on the hammer because of the inertial firing pin. With the hammer at full cock and the safety off, it is very unlikely (nearly impossible) for a fall or a blow to cause the gun to fire; even if the sear is jarred off, it will catch the hammer on the half-cock notch or safety shelf. If the safety is on, the sear will not be able to move far enough to release the hammer, and if it somehow does, the result will be as above.
As to the 1903/1908 pocket hammerless pistols, the first ones did not have a half cock notch, so if a fall or a blow jarred off the sear, the gun would fire. Colt changed that for that reason, but I am not sure of the exact date or serial number. I can probably find out if anyone needs the information.
Jim