The piano is a new instrument, when it was created its natural "place" was within the C major scale (all white keys); while A major requires 3 black keys.

All instruments have a "sweet" spot for where they like to make sound. The baroque flute for example, prefers the key of D -- not C. The violin is very at home in the key of A.

If you sit down at a piano, and find a place to put your fingers a somewhat natural place would where there are two white keys beside two black keys.

And then press them in order.. C major scale.