Illustrator makes nice brush strokes when the brush fits to drawn curves. There's two horizontal simple shapes made with the pen tool (actually they are the same, only width and fill are changed). Those shapes are dragged to brushes collection and defined to be artistic brushes.
The curved shapes are drawn with those two brushes. I used Wacom, but pressure is used to nothing. Wacom is so dammned good in filtering the stutter out that no smoothing was needed in Illustrator's brush tool options. If I tried the same with less forgiving tools, for ex. with a real brush and paint or in a computer with a brush that has in real time controlled width (=pressure or tilt), the life would be too short to recreate even these four shapes.
Do the same if you must get something usable today, but practice also with more responsive tools. They give infinitely more possiblities once you can control them.