There are many different verses in the Qur'an when different prophets have said that they are 'the first muslim'

and alot of people get confused.
So the simple response is what a brother gave a long while back, he said imagine you watch a basketball match. Now when someone asks "who scored the first goal?" - you don't go back into the history of basketball and say that it was the first person who shot the ball in the hoop, but you say it was the first guy who scored in the game that you're presently watching.
Therefore, if in one verse of the Qur'an it is said that Adam was the first Muslim, then yes - he was the first Muslim among mankind. After him there were other Prophets who were the first Muslims (those who submit to God) from among their people.
So that's the answer.

And there is no contradiction in the Qur'an.
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