If my manager (a white guy) mentions something to me (another white guy) that might be good and if Ipersonally decideto implement it because I see the value, then, yeah, sure, I'm getting credit.
Likewise, if I mention something to a coworker that might be nice, with no intention of implementing it myself, he's going to get the credit. You don't get credit for ideas, you get credit for implementing stuff.
And then there's also general human nature: plenty of white guys are treated poorly by plenty of female managers (and the other way around too). People are too quick to call discrimination, these days. Some people are a-holes, and there's not much to do about it.
as far as standing up for yourself, I'd see someone who needs to get credit for everything as insecure more than anything else. Good managers try to make their employees shine, and that's how they demonstrate value. A manager's value is mostly dependent on their team's perceived value, not on their own skills.