For an Atheist or non-religious believer, what creates value in a human?

Personally, its life itself what makes it worth living.

Science has taught me how rare life truly is, and the mere chance that it happened at all is so small, we are extremely lucky to have come into existance. This makes me want to cherish it, experience it to its fullest, knowing that I may not have another chance to do so. And it not only adds value to human life, but all kinds of life.

What creates value in a human? What you make of it. You are the only person that can control your life, and you are the only person in charge of it. 

Their actions.

it depends, 'value' is a very vague concept, within Abrahamic religions i think it could be defined in fulfilling moral obligations. You are given purpose through biblical tenets, so to say, you have guidelines to your behavior and thinking, and fulfilling those guidelines provides 'value', as you are a 'valuable', devout follower of your faith.

for those who can't inherently obtain a moral rulebook, they have to develop these morals themselves, it is up to them to forge an understanding of what them deem 'good'. without a god, and without threat of hell, what drives people to still do good things?

i believe value in one without theological constraints lies in self-fulfillment, and standing true to a unique morality. living life truthfully to yourself, without vice, hate, loathing, etc.

this is all to say that without a religious rulebook to tell people what to value, it is up to interpretation, there is no atheist's sect, no figurehead or doctrine. it is a deeply personal journey.

to put it frankly: who cares? the fact of the matter is you exist, and that existence itself is enough. having to have "value" to exist is, honestly, borderline disgusting. the beauty of not believing in religious things is that you understand that you have the power to decide what you're living for and why it matters... and if it doesn't matter, which i don't think it does, doesn't that make it so much more beautiful? not everything needs a purpose.

To be honest nothing. Someone who doesn’t believe in God cannot speak of meaning on an objective level. Therefore, a person must either hold a religious belief or when looking from a perspective beyond the phenomenal level accept nihilism.

Existentialism or absurdism are, in the end nothing more than softened versions of nihilism. A person can say “I live for this or that reason, this is the meaning of my life,” but they can not consider that meaning to be universal or objective.

Thats why the answer to your question can vary from person to person. On a phenomenal level someone might say “I live for my family” or “I live for money or for success,” and so on.