I'll play devil's advocate in part. Not to say I disagree at all.
I've no experience to call on for the way the jumper moves arms or legs while falling and what limb would be where on impact but intuition would say an arm would be outstretched and may fold inwards on impact. Nor do I know if death would be instantaneous on impact and he rolled sideways.
Having been violently thrown in an unusual minibus crash, I can say it's instinctive, for me at least, to try not to bang my/your face/head.
This is, however, filmed so inconsistencies can creep in due to continuity errors or a body could be dressed by makeup department to look like it might be expected
to look, ie with blood from the nose rather than completely realistically if the fluid should be clear. Would that depend on time elapsed?
As you say the fall is forwards, so the body should land with the feet nearest the building. It doesn't, it lands or is situated sideways on to the building as seen from our two vantage points above and on the ground.
Re fast attendance by doctors and nurses it'd cost extra to film and my opinion it'd be detrimentally slowing the pace of the action and tension for there to be a delay in staff reaching the body. To add drama John has to fight his way through the throng.
The pic screencap below is turned 180 degrees - Sherlock doesn't have a mole on his cheek, the jumper either does have or else it is dirt!
Logistics demands that risky stunts are done by stunt-people not by actors without the training and practice.
Fun is this.