Even if you're steering it, you have the same amount of control over the application as a manager does over a programmer. Did the manager make the software?
And if your manager is involved in the day to day coding of <whatever> then absolutely s/he has a right to say s/he (and others) built it. I used to be a very hands-on engineering manager (pair-programming they call it, these days) at Apple - I always used to say "My team and I".
Well, that's what I do, anyway.