Today I was wondering: Does the possessive "‘s" have any origin? Sorry to make this post so short, but it’s a very concise question I think  :)

Certainly.

In Old English, the plural of the nominative and accusative cases was formed using a suffix "-as, -is or -es." In Modern English, this has become truncated to form the standard plural "s" suffix.

The possessive declention (-es) took the apostrophe sometime in the 18th Century to form "chair’s", "boy’s", "Peter’s" etc. However, we still avoid use of the possessive (genetive) "-‘s" with inanimate objects. "The chair’s color" would be better expressed as "the color of the chair."

There are other plural forms in Old English (-an, shift of internal vowel), similar to Modern Swedish. These give us the irregular Modern English plurals (ox-oxen, foot-feet, mouse-mice, etc).

- PW
who’s forgetting his OE, among other things

The -s can be traced back to PIE, where it occurred mainly in nom. and acc. plurals of masculine and feminine nouns. For stage between PIE and modern languages, Gothic has for example giba (gift; fem.), nom.plur. gibos, guma (man) npl gumans.

Hmm, very interesting. Thanks for replying.  :)