I didn't really get a proper grasp on anything but the backstroke until I took adult swimming classes in my 20s.

It doesn't help that not knowing how to swim doesn't stop gym class from forcing you to participate. I drank a lot of chlorine during 2 weeks each year.

And it's wild, I was an avid distance runner, biker, and tree/rock climber. Swimming just didn't click for me for some reason.