after WWI there was a short lived communist revolution in Germany what would the world be like if the revolution had succeeded?
It wasn't really a communist revolution; it was a series of unrelated local uprisings, like the Kiel mutiny, the Spartacist fiasco in Berlin, and the Communist coup in Bavaria later. None of these had the backing of more than a small minority of the population and all were rapidly snuffed out. (As were right-wing attempts like the Kapp and Beer Hall putsches.) The majority of the German populace was decidedly centrist and supportive of authority, which made for tough going for Communist and reactionary alike.
It's also worth noting that the US, Britain, and France were all very much anti-communist and the latter two would have been more than willing to aid opponents of Communism if it looked like the latter might seize power in Germany.
For Communists to come to power would probably require that WW I drag on into 1919 or even 1920; the longer the war drags on the greater the privation and misery of the people, and the greater the numbers of those people who will embrace Communism as a way out of the mess.