Get some fine grade sandpaper, smooth out the rough areas, fill in the indentations with spackle. Then, paint area with primer. Then, paint the area. It is tedious work, take your time and it will look great! If you want something done right you often have to end up doing it yourself. My husband and I painted the whole interior of our home after we had our kitchen, 3 bathrooms and flooring renovated. We first fixed all cracks, sanded uneven areas, then primed the areas. We washed and rinsed all ceilings, walls, moldings and doors prior to to painting. We used top quality rollers, brushes, and paint. We took our time. You can't rush doing a proper paint job. My husband and I are “fusspots”. We knew a professional painter would never take the time and effort to do what we did. My husband, as a hobby, used to renovate cars, so he has an obsession with attention to detail. It paid off; our paint job still looks great years later! Best of luck on your journey.

This is super helpful. Thank you!

Stand back and take another picture so we can see the context. I'm not understanding what is going on with what looks like a door jamb nor why the "wall" is standing proud of the jamb.

Ok, so maybe that is a reveal but I don't understand why this would be trimmed out as if it is a door opening when it obviously isn't a doorway. Why there is jog in the wall?