Is it typical for someone to change their job several times outside of the subject of their first job throughout their lifetime?

Yes, changing your job is not unusual. In the past, it was considered important to have longevity in one job, but today with the changes that are constant in the workplace, it is not a disadvantage to have several jobs in a lifetime. I feel that determining a good general major in college and narrowing down your field as you near graduation through the choices you make as electives can give you a lot of insight into what you like and dislike. It is also helpful to look for internships in your field of interest while you are still in college. That may give you a head start in making your career decision and lessen the need to shop around after being employed. And above all, when you accept a position, do your very best. Enter with a great attitude and the thought that you can have a future here. Look for opportunities to do well and be cooperative. If you give it your best and it seems like it still is not a good fit, check out other possibilities and remember that a good reference from a previous employer can be golden. Never leave on bad terms if you can do anything to prevent it. Best of luck!

Many people change careers during their working lifetimes. Sometimes it is a significant shift that can be accomplished with additional education and training, and sometimes people just decide to utilize existing skills in a new venture. Personally, I worked as a Marketing executive in the investment management industry and then obtained a Master's degree in counseling in my early 40's which I used to move into higher education as a career counselor and student services professional. Many of the students in my Master's program were people looking for a new start, and a fresh beginning can be just what some people need to re-energize professionally.

For students in Bachelor's programs who aren't 100% sold on what to do, I recommend choosing a major in a field that they believe will work for them for 5-7 years. That's usually plenty of time to determine if a change in career direction is needed. Of course if a change in direction is possible for you, it's important not to over-commit financially to provide greater flexibility should you decide to change your path forward. During those first several years, it is often possible to decide if what you are doing will work for an extended period of time, and you can make any lifestyle changes you desire based on your anticipated future.

I find it really fascinating when someone change their job outside of the subject of their first job or may be of their specialty. First of all, it takes a lot of courage to get out of your comfort zone and try your hands on something which is completely new for you.
I will try to relate this with my own personal experience. When I was like you, in my undergrads day, I was completely into information technology and computer sciences. My final year electives were focused on software algorithms and programming languages (like Java, C++). Later, when companies came in our college to recruit us, Accenture selected me as a software developer. And then I started my career as a software techie for 3 years from there. I loved everything in the beginning, Accenture was a big brand, work culture was great and it was all going well. But after some time I started losing interest in software development. The interesting point here is not why I was losing interest, but it is the fact my state of mind was changing from the one who loved and once most comfortable with software algorithms and programming language to a guy who slowly started seeking other skills. Thus I quit my job and went to pursue MBA from a top tier Business School of my country. If you would ask why I chose MBA - I would rather say that option promised me an opportunity where I would be exposed to many different skills that may or may not be familiar with me but I thought that would be a better place to be.

I can draw the same analogy here why people drop or change the job what they were doing so comfortably and venture into something totally new - they want to take the risk of change because believe me this is what truly tests your true potential.