The rocket was first put into action by the Nazis during World War II in the form of the V-1 flying bomb and the V-2 rocket, said rocket was the first manmade object to reach space. While I don't doubt Von brain would be able to invent the rocket in this timeline's Germany, you can kiss the Space Race and everything it spawned goodbye. Man would reach the moon far later in our timeline, which means space exploration is hampered significantly. NASA doesn't exist, because I think Germany would be ahead of everyone when it comes to space exploration.
The V-2 was the first example of a
ballistic missile, true (the V-1 was not a rocket at all, but a cruise missile, and that idea dates back to World War I). However, there was substantial interest in
private experimentation in rocketry in the 1920s and 1930s that built the foundations for the V-2, and there was interest in rockets for more limited military uses (principally as short-range artillery, individual weapons, and for boosting aircraft; Katayushas, Bazookas, and JATO units, basically) as well. The former field is unlikely to be impeded by the absence of the world wars, and neither is the latter; in fact, without the destruction of WWI and the resulting economic impact, it's entirely possible that armies are
more willing to experiment with such things than they were IOTL and there is overall
faster development in the basic science and engineering. It's likely that the first spaceflights take place later, but when you really start digging the Nazis were nowhere near as important as they initially appear.
Also, you can make an argument that the Apollo program slowed space exploration down, rather than speeding it up. The race to the Moon meant that a huge amount of funding was poured into a system designed to do one specific thing, rather than a smaller amount of money being spent on systems to allow people to do many general things, and it created a bad "race mentality" at NASA that hasn't been able to adapt to "normal" conditions. Additionally, it directly led to the cancellation of many programs for robotically exploring the Moon, which would have been less costly if less effective.
The Spanish flu doesn't exist. The people who died still live full lives. But, our knowledge about medicine is impeded. Oswald Avery was studying bacteria as a result of the Spanish flu. Specifically, how it changed from one that didn't have hard coding into one. 20 years later, he discovered DNA. Many peopled believe Pfeiffer's Besillius caused the flu, so research into that never happens. This prevents Alexander Fleming from discovering penicillin. Bacterial infections remain untreatable for a longer period of time. More people die from what in our timeline are treatable illnesses. In 1998, it was discovered that the strain of flu which caused the Spanish flu was avian flu. Without the Spanish flu pandemic, we don't have a century of exposure to avian flu. It can easily strike in this timeline with a vengeance. Imagine this happening in the late 20th Century or the early 21st Century. The pandemic also aided the Indian independence movement in gaining prominence by exposing the gap between British overlords and their subjects.
It's hardly certain that there isn't a flu pandemic about the same time anyway, given the large and growing volume of world trade and communications at the time; no war necessary, just the same way that the 1957-58 and 1968-69 pandemics didn't have any particular connections to ongoing conflicts. In any case, while the flu pandemic may have led to certain people doing certain things which in our timeline led to certain breakthroughs, it's far from clear that corresponding breakthroughs wouldn't have been made in an alternate timeline without a flu pandemic by different (or even the same) people. For example, there had been a number of experiments into and reports of antibacterial substances from molds over the fifty years or so before Fleming's discovery, they just hadn't been followed up on the same way that Fleming's was. It seems rather likely to me that sooner or later someone will figure out how to isolate the active substance and synthesize it effectively; it may not be quite as early, but with no World War II there probably aren't as many people who need it, anyway.
Also, humans would still be exposed to avian flu without the Spanish pandemic. Avian flu likely predates human civilization...
The United States never becomes a world superpower. It remains in isolation, extending it's influence over Central and South America. It may extend some influence in the Pacific, but not much compared to Britain, France and Germany.
The United States was one of the most influential countries in the Pacific from at least 1898 onwards...I mean, it controlled the Philippines, was one of the main foreign powers involved in China, and, of course, actually bordered the ocean, unlike the European nations you mention. After the Russo-Japanese War, it was pretty much the only serious rival for Japan in the basin. Maybe Britain could play a role, but France and Germany were too occupied with continental concerns to really be able to exert themselves, however much they might try for a time.
Organizations related to internationalism such as the League of Nations and the United Nations don't exist. The UN, however useless the core organization may be, has many agencies that do genuine good work, especially when it comes to dealing with refugees and helping people in need. That good work in places like Africa and the Middle East never happens.
Unlikely. While there might not be an overarching concept of a United Nations/League of Nations as a major international force, rather than being a mere futuristic dream, there were already a growing number of international organizations and arrangements to facilitate cooperation between nations, such as the Universal Postal Union (founded in 1874) or the World Meteorological Organization (1873), not to mention treaties like the Hague Conventions (in 1899 and 1907) or the first Geneva Conventions (1864 and 1906). More likely is that the development of international cooperation on these areas is slower to develop and more piecemeal, with individual treaty organizations focusing on specific areas like intellectual property, refugees, cultural heritage, and the like, without being part of an overarching framework. But the general idea of international cooperation was already there and developing; it will continue to do so without the wars.
Internationalist concepts such as 'human rights' never take off. That concept, in particular, was given international prominence by atrocities such as the Armenian Genocide and the Holocaust. So, we could see a lot more human rights abuses in this timeline.
Again, no. Many human rights concepts were developing before the wars, and merely accelerated their spread thanks to the wars instead of being created by them. It's likely that you'll see slower adoption of the concept, especially without two (nominally) rights-focused states becoming global superpowers and influencing others to pay at least lip service to the concept of rights, but it will be there and will likely be fairly prominent in at least some countries.