Serious question, Keynes was born in the late 1880 and didnt publish anything until 1900s... we had boom and bust cycles long before this. How do you explain that?

Yes there were other boom and busts. But Keynes makes sure of it. According to Hayek (and many others), Keynesian spending policies are not a solution to unemployment or economic crises. On the contrary, they are a real threat to economic stability.