The history of the Latin alphabet and how it came to have two "cases" was recently explained in some detail here in /r/linguistics.

As for numerals, there actually are two forms that correspond to upper and lower case letters. So-called "titling figures" resemble uppercase letters: all the numbers are the same height. Text figures resemble lowercase letters: the 6, 9 and 0 all have the round part the same size, and the stem of the 9 descends below the line like a lowercase g. Most fonts found on PCs only contain titling figures, but Georgia is an example of a standard Windows font that uses text figures. Fonts used in professional typesetting contain both types; typically, titling figures are used in charts, etc., and text figures are used in body text.