Maybe because other targets were attacked?
In “Pedestal” the ships were the primary targets.
And: flight crews get better. An “Dynamo” the average Stuka pilot haven’t even seen a ship.

Attacking a moving vessel in open sea is not easy, but for a dive bomber a task it can manage. Of course, it will miss 4 out of 5 bombs. But one single 500kg bomb would render any destroyer inoperable.

The USA surely had an interest in freedom, as it does today. But primarily it was driven by its interests. A Europe ruled by Germany with all other nations becoming proxys was not in US interest.
The USA leadership identified the need for participation early in the war. But support was questionable. Pearl Habour changed that.

Back to the RN-question: if any invasion attempt would have started, the Luftwaffe would have been tasked with neutralizing all ports. I am quite sure that RN would have been required to move back to northern ports, Scapa-Flow and alike.
As was learned later in the war, ships were very vulnerable to aircraft attacks. The RN learned that the hard way in the Mediterranean.
Just as reminder: Operation Pedestal
http://en.wikipedia.org/wiki/Operation_Pedestal

But would have been a huge loss for the Jewish and other enslaved people of Europe.

And in truth, for the German people themselves.

Moggy

I just considered the military-political aspect.
Of course, a Nazi-ruled Europe is a frightening thought.

The British continuation of the war effort didn’t help the Jewish much. One could argue that if the effective end of combat operations had ended in 1940, quasi-peacetime travel options in Europe might have allowed more Jewish people to emigrate to USA and Britain. The decision for the “Endlösung” came early 1942.
Very delicate subject though.

The German plan possibly was to quickly neutralize the RAF and gain air superiority over southern England. Then, with any operation of RN severely limited the British government would probably have accepted a peace agreement in order to prevent an invasion.
However, as local air superiority wasn’t achieved and the Luftwaffe was rapidly losing strength (not only due to combat losses, but also operational attrition), the plan quickly became unworkable.
Germany at that time lacked the industry and the organization to quickly replace aircraft and flight crews. The deadly German “Kriegsmaschine” was much less deadly in 1940 than many think. The great victories over France and the British troops in France was mainly achieved by summarizing all available assets in one quick strike. Same applies to the Luftwaffe, which wasn’t a strategic weapon at all.

In conclusion: Although the British can rightfully claim to have won the air battle over England, the invasion was possibly never a serious option to German leadership. It was rather intended to threaten the UK government.

By purely political considerations, making a peace agreement with Germany in 1940 would not have been such a big loss for UK.

If the RAF was out of the game, any surface ship was potential prey of Stukas. They were extremely deadly – but very vulnerable to fighters.
Any RN action would have been very costly.

But again: the biggest issue of the Germans was that they couldn’t get the people over the channel. And even if you ship the people, “Blitz Krieg” needs big supply.

Luftwaffe and Armee were short of supplies after the French campaign, many Panzer divisions had lost substantial strength. Germany was short of shipping. Reichsmarine was a joke after the Norwegian campaign.

Even if they landed successfully, they would have zero supplies and couldn’t have done the magic “Blitz Krieg”.

In the end, the whole “Operation Seelöwe” was probably intended to threaten UK out of the war.