It's completely okay to "just" do your job professionally. However, skill development, transfer of skills to junior developers and mentoring is a different issue - if you want to learn from me, you have to want to learn; if you're just here for the paycheck, then I'm not going to go out of my way to educate you even if (which is the case for many junior developers) you're unable to actually do your tasks properly on your own without this help.
People with the desire and capacity to learn go over the "junior" phase very quickly (over a short internship or already during college) and become able to do decent work on their own; but those who don't and really need an actual prolonged "junior developer" role on the team... there's no incentive for the employer to do that, and there's no incentive for the colleagues to spend their effort if it seems wasted on someone who's not into it.
If you let juniors figure it out the hard way, they will learn better, or they will fail. If they fail to learn by themselves, they will never become senior.*
*Shitty code bases should be given a lot of leeway on the learning curve.
That's one (totally fine) way of mentoring, but it's by no means the only one.
A lot depends on the work environment and the relationship. I work with a couple junior engineers that are also friends, and in addition to "pointing people in a direction", code reviews, etc.:
* We frequently tackle harder issues together, pair-programming style (using a shared tmux session)
* In addition to code-reviewing their work, I have them code-review mine, and I walk them through my code and thought process
* Talks/meetings once a week or more about architecture/up-front design for projects, in which the junior devs are often included or free to attend
* We have a non-work-related Hackerspace that we attend every 2 weeks where we work on side projects / fun creative projects
Certainly this situation is not possible on many development teams, but I just wanted to point out that mentoring is a wide-open thing that has many approaches and options.
I'll probably spend 15-30 minutes every day outside of work reading about new things, or tinkering around with something, even if it's just reading Hacker News, often these things I learn end up being used at work, so I gain new skills at work. It sounds like you're in the same boat.
My father is a network engineer, and he'll spend time in the evening doing things related to his field, he has a very impressive home networking setup. My friends that are electrical engineers play around with electronics in their spare time.
I think that for any professional, to be successful and have a good career you need to have at least some outside interest in your field. Obviously we all have hobbies, I don't sacrifice those because of work, but if you're working in a job where you have no interest you'll never get far.
I don't see any problem with that though; I'm still learning a lot, and work towards switching projects/companies when that's no longer the case.
If it means you're still learning something a little extra, that's great! If not, that's okay too.
It's not a binary thing. The fact that you were/are interested enough in technology in the past is different than someone who only did the bare minimum. I consider it more of a mindset thing.