No first person language please. My iDevice shouldn't be saying "I think..." about anything. This is both a personal preference and, I suspect, better "design"/language.

Don’t anthropomorphize computers. They hate that.

"I think you fell". --> The Watch is an "I" now? Creepy.

"Fall detected" --> which is not technically correct. The watch didn't detect a fall. The watch is only seeing signals that suggest you might have fallen.

"Sudden motion - Injury suspected". --> There are probably many data points fed into an algorithm that detects falling so saying one of those factors, "sudden motion" is not accurate. "Injury suspected" is vague. Who did the Watch suspected had an injury? And not every fall results in an injury.

I still think Apple's version is the best out of any of the alternatives suggested here. I guess that's why most people here are developers - not HCI/UX people.