“Rashi brings the Talmud’s comment in Sanhedrin 108a on Noach’s status as a ‘perfect tzaddik in his generation’…

Rav Kook…explains that every Soul has its unique purpose and mission. This mission can only be accomplished at a particular time in history. Souls are time released to the generation to which they belong. If that Neshama [soul] would come into this world at a different time in history it would be unable to make its contribution or fulfill its function and purpose…

Noach could only have been who he was in his own generation. As great as he was, his unique potential could only be fulfilled at the time he lived.”