You have put your finger on the basic question. When our ancient ancestors first became aware of their existence, that at some time in the future their existence would come to an end, that caused considerable emotional anxiety, so they developed many beliefs to avoid coping with that reality. The Baghavad Gita asks, "Of all the world's wonders, which is the most wonderful?...that no man, though he sees others dying all around him, believes that he himself will die."

A lot of religious beliefs centre on dying and being reincarnated as another person or animal.

You will die tomorrow.

Yes, we die, then real life starts after death