Some of the lakes will look like seas. Water is relatively easy to cross, provided you avoid storms or can cope with them. A storm on land isn't too much fun

Some of the lakes will look like seas. Water is relatively easy to cross, provided you avoid storms or can cope with them. A storm on land isn't too much fun for a traveller either. Until fairly recently, water was generally the quickest route from A to B, if it was available. That helps to explain why the UK and Ireland's island disposition was not an obstacle to the same continuous series of colonisation events throughout history as the rest of Europe. Anyway, your super continent will have quite a lot of fresh water on it and will probably involve some very impressive rivers and inland lakes/seas. That single coastline will mean that all sea faring will be coastal until someone notices that they can nip across through what would look like a worm hole to begin with! I suspect things would play out in a similar fashion anyway and some nutter will sail or row straight away from land and keeps on going - and the mad idea of a spherical earth eventually takes hold. Perhaps it will be too far and powered flight is developed first and is able to stay aloft and move quickly enough. Perhaps airships are invented before trans ocean shipping. In another mad world, where sea or air "shipping" is not good enough, mankind straps themselves to giant fireworks, invent an amazing G-suit after some unfortunate efforts involving the pilots being smeared to the back of their clothing and then invent amazing parachutes (after a few hard landings). There are a few other details to sort out, such as how to mount the ash trays and where to put the cabin crew for first class. There is a very rich set of sci-fi and fantasy novels/stories/novellas/films/stories told around a campfire/streamed stuff that cover what might happen "if things were the same but different", for a given value of same and different. Mr Pratchett and some of his mates called us humans: "The Story Telling Ape". It's high time you started listening to those stories, or even better, telling some of your own - you do that wondering you mentioned.