Why are lots of cancer risings into visuals & art?
There could be a lot of reasons honestly. Because of their lunar nature it’s likely that they enjoy the emotionally expressive quality of art. Since Leo rules their 2nd House artistic expression is part of their value system, and it makes them feel secure. Venus rules the 4th and 11th Houses, so art can make them feel more comfortable/they get benefits from it. Scorpio also rules their 5th House too, so you can see that they might become obsessively interested in it/they find it to be an intimate and honest experience.
I have an empty 4th, 5th, 7th, 8th, 10th, and 11th house, but art, creativity, dreams, my career (in art, it's going alright), and my transformations have been defining moments in my life, or very important to forming who i am. How can these houses be empty if those are what define me?
The signs associated with those houses (or their ruling planets) may have powerful influence over your chart, your progressed chart or transits may have created an important place for those themes in your life, or your life may simply have included these themes regardless of astrological factors directly related to you (they might have been caused by other people & their charts, or they just happened to surround you based on the mundane way the world unfolds).
Also, empty houses can be interpreted two (primary) ways. One, their themes won’t be important to you / major in your life, or two, they won’t cause issues for you / they come naturally to you / they don’t need that much serious development. If those things define you because you’re comfortable with them or they helped you through other problems you’ve encountered, it’s because there are no planets to cause unnecessary pain & trouble in those areas.