I play/practice the piano for some decades and when improvising (Jazz, Romantic, and sometimes even Baroque), I observe a certain magnetism of the C Major key. I'm able to play scales, arpeggios, ...
I am trying to teach myself how to play piano and while I know what a key signature is, I don't have a firm grasp on it. I have sheet music in the key of G major. There aren't any F's on that line, ...