Sadly, Altair was douche-worthy in the first game. He was born in a family of assassins, raised to be an assassin since birth, and was a remarkable learner who always had the approval of Al Mualim (The head of the Assassin Order in Syria). With that, he was a very arrogant assassin, even though he already gained the rank of Master Assassin long before the first game started.
When the first game started, because of his arrogance, he broke all three rules of the creed. Al Mualim stripped him of his rank to have him return to the lowest of ranks - novice. Throughout the journey of the game, he had to learn how to hunt, assassinate and research on targets the novice way. The hard way. And through that journey, he learned humility and a thirst to always seek for knowledge rather than being complacent and arrogant all the time.