Is a graduate pathway program likely to help for admission to a masters in another field? Is it better than MOOCs or an internship for this purpose?
My experience with interviewing/selecting candidates to enter a masters program (in social science, it may be different in computer science) is that the process can be highly variable, and candidates may be rejected for a range of reasons ranging from test scores, to a lack of experience, to not filling out admission paperwork properly, and, unfortunately, discrimination due to ethnicity, gender, age, nationality, etc.

Different programs have different mentalities toward admitting students, some programs might want you to apply two years in a row, because they decided that this is an indication that you are "more serious".

So... It might be safe to assume that your lack of background is the problem (particularly since you were rejected 11 times), however, the only way to know for sure is to ask the admission committees.

In my experience, graduate programs in the U.S. will NEVER tell you why you were rejected, because doing so places them at legal risk. However, they will respond if you ask them "What can I do to strengthen my application between now and the next admission cycle?".

With regard to how you can get experience - many faculty members I talk with don't consider MOOCs legitimate at this time. This may be different, depending on where you are applying. Personally, I would advise you to seek education at a brick and mortar institution, if you can afford to do so.

You mention prerequisites - in my experience this term generally refers to a course that is required to take another course. Thus, prerequisites are typically taken at the same university as a graduate program in which you are enrolled, as credits won't always transfer. What you are describing seems to be taking general coursework.

Unfortunantly, there is a hierarchy in higher education. In my experience it goes:


Research 1 Universities (ranked by the Carnage foundation)
Other universities
Community colleges
Online programs


With option one being the most prestigious and most expensive and option four being seen as the least prestigious, and also the least expensive.

In summary:
1. Ask the graduate programs what you can do to strengthen your application.
2. Engage in the behaviors that the programs tell you to.