That is a pretty big assumption right there. There is no absolute amount of jobs being created, right? I mean, wouldn't you pay $1 per hour to have your shirts ironed? Then is it a problem of jobs count or jobs pay? It's pay, isn't it? If it's pay, then you are asking the wrong question. The question would be: is software making jobs cheaper? That is a very tough question. Implications are not that clear: from one end you cut jobs, from the other you are improving the productivity of your economy. With more productivity you get... you guessed it: more wealth. Then what's the problem? It's a problem of wealth distribution isn't it? It's wealth concentration in few segments of the population. That is a completely different problem then what you just said. Wealth distribution has nothing to do with value created and it's a topic in its own way.
Bottom line: it's not about how many jobs you have, but how spread is the wealth your economy is creating and how spread it's going to be in the future.
Now you can disagree with the notion that jobs are being replaced faster than created and even take the stance that such a thing will never happen. But assuming you don't disagree that this will eventually happen (eventually here meaning in our lifetime or maybe our children's; not counting thousands of years down the road), then it is going to be a problem. Yes, it is only a problem because of how our economic situation is set up, but all of that isn't the bit that changed that created our problem. And yes, changing the economic set up can resolve the problem. But the problem itself remains the same (unless you disagree with it ever happening).
A lot of them were killed by agricultural invaders, since you can feed a much larger army with agriculture.
> All those people in agriculture would still be jobless
Agricultural countries like India got invaded by industrial countries like Britain.
Even now, increasingly autonomous drones are killing people in the middle east.
It's often not good to be on the sharp, pointy end of new technology.
Increasingly? No, they're the same amount autonomous as they've ever been.
Point is, every technological innovation will be absorbed in the long term. It's been historically this way for millennia, at least. People are very good at reinventing themselves as long as they have an incentive (food, money) to do so.