I am...

I do not know who I am.

But I can tell you whom I am not

and just maybe you will see who I am.

I am not light,

but I am bright.

I am not a fast runner,

but I've gotten far.

I am not the best,

so give it a rest.

I may be insecure

but I do not belong on the floor. 

Atleast not for everyone to step over me. 

Sometimes I fall,

but doesn't mean I am not at the top.

Who am I ?

Not you, him or her

but me.

I am strong.