Have I become a disbeliever by thinking that I am better than the prophets, after learning that this is considered disbelief?

This is a whisper from Satan. It is inconceivable for a Muslim to believe that he is better than the prophets and messengers. We advise you to abandon these whispers and ignore them. As long as you have repented to Allah from this belief, then repentance erases the sins that came before it, even if it was disbelief.