Oh, my sweet, naive child, if only that were true... Otto Bismark once noted (approximately) "Those who enjoy sausages and the law, should never watch either being made".
There IS meat in sausages, but there are also every other part of the animal they can get away with mincing up fine. Breadcrumbs, seasoning and the like are in there too, but it's mostly minced... organs (The term mechanically recovered meat has a specific meaning I'm not about to go into here).
The things they put into sausages are the bits they can't use for anything else, including tile grout. Seriously, if you love sausages and someone asks if you'd like to see how they are made... RUN... RUN FAST!
As for haggis, yes, it will have oatmeal in it, just as a sausage has breadcrumbs, but whisky is entirely optional (And Scotch whiskey is ALWAYS spelled "whisky", if it has an e in it, it's not Scottish whisky!)