1. The German language doesn't work well with pun based humour. This is the kind of humour English speakers are used to.
2. They do but you need to be able to speak German to understand the jokes they're making. Understandably, it's hard to be funny in a second language.
3. IME German humour is often incredibly dry, deadpan or even anti-humour. In the past I've experienced Germans making jokes, and British people thinking they were being deadly serious. Eg. "An Irishman, a German and a Brit walk into a bar. They order beer." Expressionless face - shit example, but you get the idea.

Because a lot of German humor is pun based and when the translated into English, the joke doesn't land and so the English started this farce that the Germans ain't funny

Germans are plenty funny, the English are the problem

The Germans have excellent humour; in fact, they take it very seriously.

As they say, "German humour, it is no laughing matter!"

How many Germans does it take to screw in a lightbulb?

One. They are efficient and not very funny.

Well, I'm German.

And fricking love UK panel shows. 8oo10c, catscountdown, WILTY, Taskmaster, QI, Big Fat Quiz, HIGNFY, The last leg, ... and the standup of most of the people on these shows. And of course Monty Python is legendary.

So if I don't have a good sense of humour ... neither have you guys!

On the flip side, I also really like Mr. Bean, which seems common among Germans.

And did you know we watch "Dinner for One" every new years eve? Like that is a serious tradition in Germany.

For me, German humour is at its best when it's using subtitles in the German language - not really through puns, but by using language to highlight contradictions and absurdities. Obviously, this humour does not translate well at all.

After learning German and re-reading some Kafka stories I was struck by how stories I had read as somewhat somber in English were actually full of a weird sense of humour in the original German. It's still absurd and unsettling, but somehow Kafka is also funny.

Then again, he wasn't German.

Robin Williams had an interesting answer to the question.

https://en.m.wikipedia.org/wiki/High-context_and_low-context_cultures

You wanna hear a good German joke? Here it goes: Ein Mann kommt zum ersten Mal in den Knast, er als kleiner Wirtschafts Verbrecher zwischen den ganzen harten Langstraflern. Erster Tag in der Dusche, ein riesiger, nackter Kerl kommt auf ihn zu, behaart wie ein Gorilla und ein riesen Dödel. "Du bist jetzt meine neue Freundin. Mit Spucke oder ohne?" Der Neue, verzweifelt, wimmerte "Wenn's den sein muß, mit..." Der Gorilla brüllt nach hinten "Ey, Spucke, du bist auch mit dabei."

Q.E.D.

Germans do have humor. It is actually not that different from English humor in style.

The idea that Germans have no humor comes from a number of reasons. To understand a foreign joke, you need a thorough grasp of that language. And this applies to any foreign language - I could not understand e.g. a French joke, but I would not deny that they most likely love humor, too.

Then, most English or American peoples impression of Germans stem from times of war or shortly after - only a small minority bothered to update their views later. During the war, allied propaganda had obviously different goals than promote German humor or Germans as funny people. And people in the early years of post-war Germany had not much to laugh about in life, their prime job was to survive in less than funny circumstances.

May I introduce you to Flula Borg

Ungefahrt is a funny-sounding German word

From what I understand, German people are very serious and value efficiency in the workplace above all else. Or so the common stereotype goes anyway.

Obligatory german humor is the wurst.