On any given song, you only have 12 note choices. Scales are a way to narrow down those choices. I don’t look at scales as a string of notes; but the choices available for a given feeling.
Now, it’s up to you to really get to know what each scale means to you, and what each note means individually. What does the 5th scale degree feel like? The 2nd? How about a b2 instead of a 2?
Learning the numbering system is crucial, IMHO. It allows you to see and hear the
distance from tonic, and then know what a scale will sound like before you play it. It doesn’t matter what the key is, but I know what a blues scale will sound like.
you have simple songs like blues, or I-V-vi-IV (wagon wheel) where you can just jam on one scale and the tension-release kind of takes care of itself (if you’re listening and choosing accordingly.) then there are more complex forms (like jazz) where you have to “play the changes” and choose various scales/arpeggios as you go.
Great resource below on scales, helping you see how they compare, and chords they go with:
https://ouhorns.ou.edu/Horn_Studio_Site_2015/Syllabus_&_Technique_files/Jazz scale guide.pdf