You are mistaken. Atheism makes no claim about gods not existing. It simply rejects the claim that they do exist. This is called the null hypothesis and it is the default position. If you would like to have a legitimate conversation about this then you need to understand this difference. Otherwise you are just strawmanning atheists and that's just intellectual dishonesty.
Humans have always been predisposed to believe in God. Look at societies and how they developed across the world. Athiesm is going against that human instinct because they expect to find a creator in the creation for some reason.
Theism is a learned behaviour, taught to children. It is not the default position. Religion spawned from asking 'why' and since knowledge was limited in the before times superstition came to be. That's why most societies around the world have differring views on religion, if it was the default state there would be one religion not multiple.
Which is why different regions have completely unrelated gods who directly contradict each other on how god works, what god is, how many gods there are, what god wants, what god doesnt want, what god likes and dislikes, how god made us, how god made everything else, what god intends for us to do, and how god wants us to live.
Because its such a natural thing that we all correctly know intuitively. Right.
Everybody is born without a belief in god. It should require extraordinary evidence to prove such an extraordinary claim. People just accept it because it's comforting.
No. There's a difference between not believing in god (atheist), and believing she doesn't exist (antitheist, I guess). It's not that I believe that there is no god, it's possible, I just don't believe you when you tell me that there is. Why should I?
The vast majority of people who identify with that label mean they don't believe in a god or are not convinced. Not that they are asserting that there is no god.
Me personally? I am willing to assert that there is no 3-omni personal God. I am not willing to assert that I know 100% that there isn't some weird-ass star trek like alien somewhere that has such cool tech we should properly call it a small g god. I don't think that there is one but I can't really claim that I know that.
No. Atheists being skeptical of the baseless claim that God exists makes perfect sense, the gnostic claim that God at least provides a hypothesis is perfectly baseless.