Number One Narcissist Trait

Everyone has traits of narcissism, because everyone is a human. The difference between a "Narcissist" and a typical human who has not matured past their traits of narcissism is very simple:

The Narcissist believes he or she is entitled to his or her narcissistic behaviors.

A human who is not a "Narcissist" has a measure of humility, and feels remorse. The non-narcissist wants the other humans around him or her to feel confident, to succeed for real, to be happy and at peace. The non-narcissist feels bad, genuinely, when they have acted in a hostile, arrogant, or inconsiderate manner toward another person. The non-narcissist does not think it's okay to treat another person with control, condescension, or disrespect, because they have deemed that person to be "less valuable" or "less intelligent" or "less capable" than themselves or others. The non-narcissist does not think it's okay to treat another with disrespect, hostility or inconsideration as "retaliation".

The non-narcissist does not believe their own problems are more important than another's, or that their accomplishments or abilities are more important than another's. The human ego does swing in that direction with the ups and downs of life, but it doesn't stay there. The non-narcissist realizes their ego has gone over the top, and makes a correction. That's where remorse comes in.

The non-narcissist desires to improve their own behavior, and they seek to learn what others know. Non-narcissists can be shy, outgoing, or neutral; they can have all kinds of "bad habits" or behaviors that affect their own lives and the lives of others; they can be very intelligent, gifted, impassioned; they can be very kind and generous and giving; they can be angry, happy, sad, excited; they can act selfishly or unselfishly; they can do and feel all of the things within the realm of being human. The difference is, when a non-narcissist messes up, they feel bad, and do not simply try to wriggle out of accountability. When they hurt another person, they don't blame the other person, or justify what they did; and when they do slip up and deflect blame, they will eventually recant, apologize, make amends. When another person has loss, pain, or problems, they don't feel annoyance toward that person, they feel empathy or at least sympathy. Their reaction toward that person is not avoidance, judgment, or bullying, they don't try to shut that person down or make them go away, because they feel compassion for them. They want to help, they want that person to feel supported.
They do not feel like the person is trying to out-do their problems or needs.
They do not compare their problems against others, or attach value and recognition to their problems, or to anyone else's. They do not try to use their problems as tools to manipulate others, and they are mindful of the problems that others are dealing with.

Non-narcissists do not feel "outshined" by those who are going through dark times, or having any kind of problems, on a regular basis. Non-narcissists do not always fear that their needs will not be met when someone else is being paid attention to; their focus is not mainly on themselves when someone else is dealing with pain, sadness, fear, or tragedy, whether it is a "big event" or a "small event".
(However, a non-narcissist can be treated with enough disrespect during someone else's dark time to make them refocus their attention on themselves in defense, which is a healthy response.)

A Non-narcissist does not feel that disrespect, manipulation and conflict are just "normal" things that people do to each other, and therefore try to force these behaviors on others, and demand acceptance of them. The Narcissist, however, will criticize the person they are trying to bully for rejecting the behavior. 

The Non-narcissist does not feel entitled to disrespecting another person, for any reason.  
The Narcissist does, for whatever reason they can come up with.