Why is C the base note of standard notation and keys?
The note names are derived from the alphabet, which starts with "a".
But why is our note "a" not on any important position? In current times you would think the major scale is the most important, but it begins with "C".
Supplemental To clarify the question: If you name something, a note, and you have a clear system like the alphabet you start somewhere meaningfull. The point is: Was in some part of history the note "a" on any important position of any scale.