You can call them an inspiration.
An individual who had a very important influence in your life could be just about anyone depending on the circumstances. A word or expression for that person could be mentor, confidant, counselor, adviser, teacher, coach, guardian angel, or the devil himself.
How can anyone in my life actually be more important than me?
I am the only one that is ‘me’ in my life.
I am the only one in my life that is actually living my life.
This may sound like a move towards narcissism, but it’s just a reminder of a simple fact.
Sometimes we give our life to other people without thinking about it.
In order for you to be able to give life to other people, you must first have it yourself.
You must realize that your life is first yours to live. And not for others to live.
The most important person at your birthday party is you.
It’s celebrating you being alive, not celebrating others celebrating you.