Fundamentalist Christianity says we were put here by God exactly the way it is described in Genesis(whichever creation account you want to use) for a purpose. That purpose is to be in relationship with him. We are the only creatures capable of consciousness, abstract thought, and self-awareness. We are the only creatures capable of that relationship.
The idea of not being necessary is marvelously humbling, but not really at odds with most religious thought.
Another question I like to think about is not whether we are necessary, but whether or not we were inevitable. This question is scientific, (in a way; given what we know about natural process reliability) philosophical (contingency), and theological.
So I’d like to ponder that a little. If our purpose here is to be in a relationship with God, who most Christians believe to be our creator in one sense or another, is the thought of not being necessary at odds with religious thought? Beyond being placed here to be in a relationship with said creator the creation account has this to say:
Then God said, “Let us make man in our image, in our likeness, and let them rule over the fish of the sea and the birds of the air, over the livestock, over all the earth, and over all the creatures that move along the ground.” So God created man in his own image, in the image of God he created him; male and female he created them. God blessed them and said to them, “Be fruitful and increase in number; fill the earth and subdue it. Rule over the fish of the sea and the birds of the air and over every living creature that moves on the ground.” ~Genesis 1:26-28
*I am in no way saying that we are necessary. I think we as a species want to feel necessary. What I’m pondering here is really the point of our creation, if indeed we were created by God.