The plant matter of a fruit is still alive, though. At some point you're drawing an arbitrary line that separates the living things that are okay to eat from those that are not.
That depends on the definition of "alive". Fruits don't respire which a lot of definitions include. And yes, it's going to be an arbitrary line.
Perhaps not the fruit as a whole, but the individual cells certainly do.
Going to the cellular complicates matters. That'd probably mean that you'd have to wait for fruit and veg to go mouldy before eating it and then do we consider fungus to be alive?
Like I said, arbitrary lines. The only way to sidestep it completely would be if you could directly synthesize sugars, lipids, and proteins. Then you could sustain people killing-free.
It's not whether they're alive but if they can suffer.