I have two children.
Explaining maternal love is difficult. Often I don't even really like my kids. But there's always that instinctive love where I'd take a bullet for them without a second thought.
I absolutely do NOT love the first born more. But there is a particular connection that I just can't express in words.
He was the one that made me into a functioning "woman" as opposed to a girl. Essentially, my life was no longer mine to do as I choose- I had become XXXXX's mom and everything I did would have an impact on the person they would become. Of course,this all applies to subsequent children too. But everything just changes overnight with the first.
I can't speak for "mothers" in general-only my own understanding.
In short, NO, I don't love my first born more. But they will always be special.