What is the difference between "J'ai faim" and "Je suis faim?" By looking at different sources, I found out that most people say "J'ai faim," although I wanted to know if there was anything wrong with using the latter.

Answer 1

"J'ai faim" is the proper expression to say "I am hungry."

Just like in English we would not say "I am hunger", it would be incorrect say the equivalent in French.

Another notable difference in French from English is about age.
We would say "J'ai quinze ans" to mean I am fifteen. The verb "être" is not correct for this usage.