Original anime adaptations aside, anime productions are traditionally funded by major publishers to promote their particular products (novels, manga, games, merchandise) or talents (singers, musicians, voice actors). Anime production is not necessarily limited to manga. Recently there has been an increasing trend in the adaptations of light novels over manga. One of the biggest and most compelling reasons is that light novels have much more content to work with for 1 to 2 cour series.
The specifics vary between production commitees, but adaptations of non-japanese are very rare, unless the work is very well-know or respected within the Japanese community. Partially due to the costs and complications involved in costs and licensing and negotiations, if you don't have a big well-known label backing you.
If your country has an established animation industry, you're more likely to have them do an adaptation of your work than in Japan, assuming your work is well received enough to merit one.
However if you still are deadset on pursing such a course. One approach Korean companies have been doing however is the use of webtoon comics to promote a particular novel series. Notable examples within the English scanlation communities are Solo Leaving and Legendary Moonlight Sculptor. With enough traction from audiences there is a slight chance for your particular series to catch the eyes of publishers.
Webcomics are a very viable way to promote your work to a wider audience as they tend to make things easier to digest for the masses, assuming you are or can find a company artist willing to collaborate in your vision. Webcomics can also provide you with the opportunities to experiment and dabble in concepts you would not usually be able and see how your audience react in a faster matter. How well or poorly your work is received relies heavily on your ability to manage, plan, and collaborate. With enough traction maybe one-day you can achieve what you are striving for.