I have had a couple older diesel tractors. Both had a manual shutoff valve/lever. Pull the lever and it will shutoff the flow of fuel to the injector pump which will kill the engine.
I have a 2 cylinder diesel engine that powers a outdoor construction style light tower. It has a optional kick starter. Never tried it but doable. That engine does not even have glow plugs to warm it up and it starts easily.
Older diesel engine with mechanical injector pump could absolutely be started without electric starter. Better have arms like Popeye. I can’t imagine starting a 4 or 6 cylinder diesel engine by hand. My grandpa has stories of his old model T, they would take a pan of coals from the fireplace and put it under the engine to warm it up before going out and cranking it by hand. Small gasoline engine is much different than diesel. Given what I just said, I think many of the older diesels had compression relief valves that would make it easier to turn by hand.
Some of the older diesel engines would have a gasoline pony motor that was then used to start the diesel. Imagine a lawnmower engine that you start with pull rope. It spins up then you engage the clutch on the pony motor to start the diesel engine.
There is a youtube video out there of some old time using a blank bullet to start a old engine. The firing of the bullet blank was enough to get the engine rotating to start. I think that was actually a kerosene tractor but I can’t remember.
I am by no means a diesel expert. I actually have limited exposure to diesel equipment. I know just enough to be dangerous.