I am currently about to begin my senior year of high school and am unable to take anymore college-level English courses; last year I took both dual-enrollment composition and dual-enrollment literature, and my high school does not offer anymore dual-enrollment courses (my high school also does not offer AP classes). Will this look bad to colleges because I have essentially stepped down from college-level courses back to high school level?
No it will not look bad. You can’t take what is not offered.
Make sure your GC indicates you couldn’t take more college -level classes on your recommendation.