Define "adult". I got my undergrad degree in Fine Arts, walking in at 18 with very little in the way of skills, but learning along the way. 4 years of classes and practice can do wonders for just about any skill set.

got decently good at it

If you want to be good, you won't do it. Because learning == endless process of doing something badly relative against adult standards. Not being able to play blues guitar as well as B.B. King don't mean you ain't got the blues.

If you want to do draw, I can give you permission. Nothing will change until you give yourself permission to draw badly. Until you give yourself permission to draw for the sake of drawing. Until permission to take your drawing seriously. Until you accept the technical flaws of your technique. Accept that your flaws are what makes your art your art. Good luck.

Yes, I started learning drawing as an adult with zero natural talent. For me, it wasn't about becoming exceptionally good but about exploring and finding pleasure in the process. I took drawing classes following the "Drawing on the Right Side of the Brain" method, which I highly recommend.