Who is the 1st person that discovered the earth?

No one "discovered" the Earth, but among the first to map both hemispheres was Amerigo Vespucci (1454- 1512) an Italian cartographer, from whose name "America" was derived. The first Europeans to circumnavigate the Earth were on the crew of Ferdinand Magellan (1480-1521), a Portugese explorer who died during the voyage.