Conclusion 2: If you say that your target customer is developers, you need to take a big product marketing time-out. Not all development professionals are the same. Now march up to your room and think about that.
As important as conclusion 1 may be, it's not exactly profound. Sure, we all know that people are different, but what are the significant differences? And how should these variations affect the way we market our technology to rank-and-file developers versus the fancy-pants enterprise architects?
Many efforts at persona development break down at the very beginning, with the question, How many different personas do I need? There's no obviously correct answer to that question, especially when you haven't seen the data that indicates which demographic differences are significant, and which aren't. (Leaving aside the practical question of how many personas you can actually produce.)