The Russians and Americans were in the "Cold War" at the time, and they were very afraid of each other. Some people would aim their telescopes for the heavens and see parts of the final frontier, space. Once rockets were invented, humans could safely travel through outer space. Of course people have tried firing other humans into space by large cannons. It didn't work because it takes an extreme force to pull from the earth's gravity.
Yuri Gagarin was the very first human in space. Before him, people would send animals and sputniks up into space. But no one really knew what it was like. Gagarin flew at a speed of about 16,000 miles per hour and flew for about 108 minutes! Gagarin actually didn't go the entire way flying. He was supposed to stay in the capsule, but he used his parachute because the ship would've crashed to fast. No one dis-counted his flight, though. People will never forget April 12, 1961, the day he set off.