The Germans had no landing craft and no capacity to sustain an overseas invasion such as Sea Lion. Even if they were lucky enough to land a small force, they would be isolated and out of supplies and ammunition within days. Britain was by no means defenseless,
My understanding is the British Army lost almost all of its equipment in the Battle of France (excluding troops in the Mediterranean, and other overseas colonies). The evacuation from Dunkirk forced them to leave behind all of their artillery and tractors.
It would have likely been somewhat similar to a "Mega-Crete 1941" campaign, where the British army evacuated from Greece was overrun by German paratroopers with nothing but pistols (German paratroopers landed with main armament separate of operators).
and it is almost definite that in the unlikely event of a successful crossing, Germany would have been pushed back to the sea.
Depends on what we're talking about. In 1940 they definitely did not, but due to weather/hydrology conditions, a naval invasion in Fall of 1940 was unlikely anyways.
As to capacity, they managed to pull of Norway 1940 in even worse conditions.
Again, we have Normandy 1944 as "Reverse Sea-Lion". Everything what you're saying can be applied to that operation, and yet the Allies succeeded (despite even landing in a coastally fortified area).
Weather was certainly a factor, but Germany was never anywhere close to having the material and logistical infrastructure to support an invasion of the UK. Sneaking two raiders through the channel and landing an invasion force are not equivalent tasks.
Agreed that it's not an equivalent task.
But did the Germans ever have anywhere near the material and logistical infrastructure to perform any of their operations? Such as the Africa Campaign?
Did the Japanese have the material and logistical infrastructure for their Guadalcanal campaign?
Yet somehow there was some pretty big fighting.
Germans supplied Norway the entire war, with zero issue. Why the UK would be such a problem, I don't understand.
As for the Kriegsmarine's long-term prospects, the various plans and contingencies for a later war could indeed have resulted in a stronger Germany navy (like war starting in 1942). But the Royal Navy was by no means idle, and British shipbuilding capacity far exceeded German shipbuilding, to say nothing of American shipbuilding which by the end of the war would exceed both combined. Had the war been delayed and Germany built more ships, the UK would have had more time to finish even more ships and be even more prepared. The Germans learned this the hard way in the First War and were foolish to even attempt to compete with an island nation for whom the navy was the senior service valued above all else.
It's not a "I have more ships" competition.
Germans had the advantage that they were invulnerable to the British navy and could choose where to apply their force: raiding in the North Atlantic, South Atlantic, Naval invading the British Isles or something else. The British had to protect against all of these options and account for potential reaction delays.
After all, we can simply check how many battleships the Germans tied down, when they were desperately needed in the Indian Ocean, Mediterranean and the Pacific.
Britain's shipbuilding slowed during the interwar period because of the political expedience of budget cuts. Had Germany appeared to be a more serious threat, the British government would have quickly cast aside any misgivings to maintain the naval balance of power.
There is simply no plausible scenario where the German navy comes out on top.
Arguable.
It's not just about shipbuilding capacity, but also "forces/tasks". The Kriegsmarine had way less tasks than the Royal Navy, which had to spread out between the Pacific, Mediterranean, Atlantic, Indian and North Sea. Half of the British Navy had to stick by the Home Isles and be based in Scapa Flow.
Even the few outright second rate (you can't call Scharnhorst and Gneisenau modern battleships for 1940) ships they had managed to successfully interdict British shipping lanes repeatedly.
Somehow Germany launched the Norway naval invasion, landed navally (besides paradrops) at Crete and the British navy couldn't stop them. Not only that, from 1940 to 1945, they had no issue supplying Norway by sea. Why they would suddenly not be able to supply a force in the UK from French ports from a shorter distance, I have trouble understanding.