One of my favourite spaceflight facts is that, due to some heavy technicalities on what the universally accepted definition of an astronaut is, and the intense secrecy surrounding the Soviet Union at the time, the entire Vostok program, AKA the thing that first took humans into space, technically doesn't count and everyone just agrees to ignore that.
Submitting my claim that Vostok is actually the cutest spacecraft ever, which is an entirely normal statement.
When they sat down and defined what counts as a successful manned flight, part of the requirements included the astronaut(s) landing in the vehicle. But Vostok didn't do that. Instead, the Vostok cosmonauts ejected from the vehicle after re-entry and parachuted to the ground separately. This continued until the later Voskhod missions, where they ripped out the ejector seat so they could fit more guys inside (and on the second one, one guy and an inflatable airlock so one of them could do the first spacewalk), and put in a rollcage so that landing inside the vehicle wouldn't turn them to goo.
But by the time Voskhod 1 blasted off from Baikonur, all of the Mercury flights had already been flown, so this means that, according to the rules, America technically completed the first manned space flights.
Another technicality was added to the list a couple of years back, when the guys that make the rules futzed with said rules in order to deny Jeff Bezos and Richard Branson astronaut status, because fuck 'em. Now, in order to be an astronaut, you have to actually do something on the flight, otherwise you're just a passenger. And many of the Vostok flights were indeed more like passengers than crew. The Vostok spacecraft is pretty much a big satellite with a passenger compartment and a re-entry module, and it's fully automated.
So why didn't these technicalities get called out? The USA and USSR were never shy about trying to embarrass each other, or make each other look foolish on the world stage. One of the biggest reasons why we know the Moon Landing Conspiracy Theory is total stupidity is that the USSR congratulated NASA on the successful landing, because if it had been recorded on a soundstage in Area 51, the Soviets would've been the first to call bullshit.
Well, part of it is just that the Americans didn't know about the specifics of the Vostok program at the time. Whereas the American space program was a very public affair with cheering crowds showing up to watch every launch, the Soviets were much, much more clandestine than that. Baikonur is in the middle of the Kazakh desert, and the Soviets were keen to lie about anything that went wrong.
When their attempt at a moon rocket, the N1, endured four successive failures on launch, mostly caused by the Soviets lacking the funding and the facilities to properly test the thing, and instead just had to launch fully built rockets and hope they worked, the Soviets simply scrapped the last two and declared that they'd never intended to go to the Moon and were all about Earth orbit instead.
The N1 was actually more powerful than the Saturn V, but because it never reached operational status and the Soviets preferred to pretend it didn't exist, the Saturn V remained the world's most powerful rocket until Artemis 1 flew last year. A similar situation is happening now, with SpaceX's Superheavy being more powerful than the SLS, but also being basically a giant bomb at the moment.
Most Americans had no idea how Vostok worked, and didn't even know what it looked like. They didn't get to see what a Soviet spacecraft actually looked like up close until the Apollo-Soyuz mission in 1975.
Behold, the setting for the most expensive handshake in history.
By the time the full details came out, the world had known that the Soviets did it first for decades, and challenging that doesn't really do much for anyone besides the people that want to go "Um, ackchully" about everything.
Additionally, the rules weren't even written yet at the time, so there's even less reason to start changing shit up now. Vostok might be technically breaking the rules, but nobody cares, and downplaying the immense technical achievements of Sergei Korolev, Yuri Gagarin, and everyone else that worked on the early Soviet spaceflights on account of a rules quirk that wasn't even written yet is just kinda dumb.
(Random sidenote, Korolev was the chief designer of much of the USSR's early spacecraft, including the R7 rocket that carried both Sputnik and Vostok into space, and still carries some of the Soyuz flights to this day. And, like pretty much every major achievement of the USSR, he wasn't Russian. He was, in fact, Ukrainian.)
