How old is the Sun
The Sun is about 4 1/2 billion years old. Humans have only been around for a tiny fraction of this time. As a comparison, if you think of 4.5 billion years as the length of a 12 inch ruler (or 30.5 cm ruler), then the time humans have existed wouldn't even be the width of the lines marking the inches.
The Sun will remain more or less the way it is now for about another 5 billion years. After that, it will exhaust the hydrogen it currently “burns” and will enter a new phase of existence. During this phase the Sun will begin “burning” helium and will expand to about 100 times its current size and become what is called a red giant. Once it runs out of helium, it will collapse into a much smaller object called a white dwarf.