It certainly doesn't make you a bad
anything. Your level of ambition is a personal thing. It's yours alone, and no one gets to look down on it[0]. This idea that a person's worth is tied to how far they want to and are able to go in their career is something that needs to die.
If you're happy with where you are, and happy with your salary and status, then it's fine to stay there! Certainly, as you say, continue to learn new things, make quality contributions, and get your work done.
Many companies will have what they call "terminal levels" for individual contributors (most probably don't really advertise this unless you specifically talk about it with your manager). The idea is that you can work at a level where you can get your day-to-day work done with minimal guidance, even if you need guidance on the bigger picture stuff (like what you should be working on, and why). You should certainly talk to your manager about this, if you feel comfortable. And if you don't, and/or they keep pushing you to climb the ladder further, then yeah, you should probably find a new gig.
One caveat: ageism is still an unfortunate thing in our industry, and as you get into your 40s and beyond, if you're still "only" a "senior software engineer", you may have trouble getting new jobs.
Companies don't want to get stuck with people who are perpetually "junior" and need a lot of hand-holding to get their jobs done. That's of course ok for a while someone is learning and growing, but if they aren't growing out of that, they're a liability and time sink. But once you're past that point, you should be ok. The only problem is if you end up at a weird place where no one wants to progress up through staff/principal/architect/fellow, in which case I wouldn't be surprised if everyone starts getting pressured to up their ambition. But that sort of scenario seems somewhat unlikely?
[0] Well, unless they are in your immediate family and your lack of ambition is putting their livelihood at risk in ways they can't mitigate. But I'm assuming that's not the case here ;)