A corporation is simply a legal entity that anybody can register. You could have one tomorrow morning if you wished.
I do own a corporation, even if I’m alone. It’s just that I own all the shares and equity privately. I’m also a business owner because I run a business with that corporation. But a business owner can also run a business without a corporation if he chooses to.
Now, you can do a lot of things with a corporation depending on your goals and aspirations. It has different rules, laws and purposes than a normal employee or a self-employed individual.
Examples: hire people, tax benefits, grow larger, own assets, sue and be sued, raise capital, loan/borrow money, go public, etc.