With the issuance of the Monroe Doctrine, was America a world power? explain your reasoning

As I wrote elsewhere: Not really.

It wasn't until the Roosevelt Corollary to the Monroe Doctrine a hundred years later that the United States was seen as emerging into status as a world power.

The importance of the Monroe Doctrine is that the United States was going to mostly stay out of the wars in Europe, despite receiving aid from France during the Revolution and having been formerly British.