Everyone dies. In fact, nothing lasts. Inanimate objects are only apparently permanent. Some products of manual and mental labor endure for considerably longer than individual human beings. When it was pointed out to a Northern Irish coal delivery man that he was careless about leaving coal stains in a house, he replied, "There'll be fluers 'n' duers when we're a' deed." (There will be floors and doors when we are all dead.)
Religions usually offer some form of immortality. Buddhism emphasizes mortality while also referring to a timeless Nirvana that is not endless survival but is also mysterious. Some religious post-death states negate or transcend individuality whereas others preserve it.
Spiritualists claim to prove immortality of the soul. Christianity is differentiated from all other religions by the proclamation that "Jesus is risen," not that he was revived two thousand years ago but that he is now and forever alive, having conquered death not as a spirit surviving a body but in a new kind of spiritual body. Quite a claim, if it were true. Christians can access Jesus' immortality but in entirely different ways: Catholics receive Communion; Evangelicals merely believe.
Jesus is also believed to be both Messiah and Savior but the Resurrection is supposed to verify both the Messiahship and the salvation so the Resurrection remains crucial. The belief that he is risen could only have been founded after his death so it was not founded by him. Peter proclaimed the Resurrection and thus founded Christianity. Jesus' teaching, while he was alive, was not Christianity but the same as John the Baptist's, "The Kingdom is at hand." Christians claim that the Kingdom came in the Resurrection but that was not its original meaning.