"How can anyone still believe in religion?" Our own positive spiritual experiences with God, silly.
"There's no categorical proof." That's disingenuous. Proof is for science, which can say absolutely about God. Experience is for religion. Use the right tool for the job. Know God for yourself, through your own experiences with him. That's the logical thing to do.
"There's numerous religions so one is right but all the others are ludicrous, despite them being essentially the same stories/morals compiled into different books." No, that's not true. Most religions have at least some truth in them -- some more, some less.
"There's magic and miracles in these stories that are literally impossible and nothing like said magic has never been since again." No, God and Christ do not use magic, but they know incredibly more than you do, even about physics. They work according to natural and eternal principles.
The miracles are not impossible, silly. They are impossible for YOU.
"The bible, for example, claims that Noah is over 500 years old. Back then people would've lived to 30/40 at best with no advances in medicine or healthcare what so ever." Prove it. Life was apparently quite different before the Flood. For example, we have no record of burials before the Flood in the Bible.
"People still go to a building every Sunday to WORSHIP something/someone they've never seen but someone wrote about him 2000 years ago in a completely different language, so it MUST be real" No, people find out through their own experiences that God is real. You ought to try it. That's the logical thing to do. And people sometimes DO see God.
"So apparently, when a creationist story is old it's most likely correct and we should kill other people who don't believe the same story and other atrocities, ..." An appeal to ridicule is not a logical argument, silly. People learn the truth about God and creation all the time. And we certainly shouldn't kill people for daring to have a religion different from ours.
How can anyone still believe in atheism? There's no categorical proof that it is correct. There isn't even any evidence that it is correct, while every year millions of honest and sane people have positive spiritual experiences with God. Follow the evidence. Know God for yourself. That's the logical thing to do.