Question

why human being take only oxygen gase not other gases while they also available in atmosphere ​

Answer 1

Humans only take oxygen gas because this gas not harmful for humans

Answer 2

Once upon a time mother earth asked humans to avenge her against Jupiter who insulted her when they were kids. So sir Alexander Fleming found e=mc^2 and launched atomic bombs to Jupiter. Luckily swami nithyanda stoped the missile and converted the explosion to oxygen gas.