In bass terms, an example of a skill is being able to chug, or to play triplets, or to slap, etc. These techniques are certainly trainable/learnable. The same is true of any number of other bass skills.
The same, too, can be said for learning the alphabet, spelling, sentence structure, grammar, composition, etc. Each is a skill taught to the young, to prepare them for higher communication in life.
Jumping to a genre I’m familiar with, jazz players are definitely skilled musicians, in many cases, consummately so. But jazz music is comprised of not only skillfully played notes but from original melodic lines composed on the fly: improvisation.
Many jazzbos study and learn the skills to master their fretboards/keyboards/horns. I was in college with some great ones. Were they skilled? Absolutely. But were some undeniably better at interpretation/improvisation than others? Without a shadow of a doubt.
Those guys practiced their ever-loving balls off. I know because i could hear them through the walls of the campus practice hall.
But I also heard other players practice equally as much, but they never got particularly much better over time.
Why was that? They for damn sure worked hard and they loved the genre. They poured their hearts, souls and skills into their playing. But it never came across as inspired or, frankly, impressive. I don’t know, but i imagine @Gio can attest to this phenomenon.
I’m not dissing those guys or anyone else. It’s just a fact that some folks “have it” and it shows.
All to say, merely working extremely long and hard to completely master the alphabet, spelling, et al, does not a Shakespeare make. Nor a Coltrane. Nor a Michelangelo.
I firmly believe that each person has some degree of aptitude for something, whether discovered, or not. And that aptitude is talent. YMMV