Who wouldn't be afraid of death? You have no idea what is going to happen and no one can prepare you for what might happen. You don't know whether you end up in Heaven or Hell, maybe you turn into an animal! You may get to see your deceased relatives, you might not.
It is natural for all people to have a certain level of fear regarding any new experience. Death is the ultimate experience that people cannot face until the end of life. It is also the one experience we cannot learn about from other people who have already experienced what it is like.
People fear death for many reasons, such as being in pain or alone when the time comes or leaving family and friends behind. Ultimately, a fear of death is a fear of change and the unknown. Most people enjoy living and can't imagine not being present on Earth when there is still so much to do and enjoy.
While most religions attempt to explain life after death, there is very little objective evidence of what happens to us after we die. Many question whether heaven and hell exist, or if our consciousness simply ceases to exist. Even near death experiences, while promising, are subjective and unproven as to whether they reflect a glimpse of the afterlife or are mere hallucinations.
No one in their life is ever ready to die. Not even Jesus wanted to die in the Bible. We are always focused on ourselves and what we can do to help ourselves. When near-death situations occur, most people experience a time of appreciation of life, because they realized they never wanted to die. Everyone has plans for themselves in the future, and death would never let those happen. In some situations, some people will even sacrifice others so that they can live, revealing true selfishness. So yes, fearing death makes perfect sense.