@mxashlynn the only person who can REALLY help you understand copyright licensing is a suitably experienced lawyer. but for your entertainment, here is my layman’s understanding:
• promoting commercial things on a page which hosts CC NC content, where the CC NC content is unrelated to the commercial things, is ok. for example, i think wikipedia can (and does) throw a fundraising banner on a page which includes a CC NC image. the primary purpose of wikipedia pages is demonstrably not to fundraise, so them linking to a fundraiser from time to time is not a problem.
• using CC NC content specifically IN an advertisement for a commercial thing is probably commercial, even if the advertisement itself is freely available. i wouldn’t do this.
the question for you is probably whether you think your webpage falls in the first or second category. are you being primarily informational, and some of that information happens to involve commercial affairs, or are you trying to obtain a commercial advantage by having a website? who can really say, other than the courts? unfortunately many questions of copyright can’t be determined until someone sues to find out.
as a footnote, putting advertisements (not your own, but other people’s, like DoubleClick) on a page definitely makes it commercial. this isn’t too relevant in 2024 because nobody does that anymore, but it was relevant in the early days of CC, when running ads on your blog meant you couldn’t use any CC NC content. youtube has the same problem. this is why it is encouraged to really think twice before licensing something as NC.