“Happy” Originally Meant Lucky
If someone called you happy in medieval England, they might have been commenting on your good fortune rather than your good mood.
The word developed from Middle English hap, meaning “chance” or “fortune,” plus -y. Hap itself came from Old Norse happ, meaning “chance” or “good luck.” A happy person was someone fortune had favored. oxfordlearnersdictionaries.com
In the late fourteenth century, happy could describe prosperous circumstances or events that turned out well. During the sixteenth century, the familiar emotional meaning—pleased or content—became established. The word’s emphasis shifted from favorable circumstances to the feeling they might produce. Etymology, Origin & Meaning
The older meaning still peeks through when we call an unexpected meeting “a happy coincidence.” We mean a fortunate one; the coincidence itself has no feelings.
Here is the memorable surprise: happy and perhaps belong to the same family. Perhaps combines an element meaning “by” with hap: essentially, “by chance.” And hapless means lacking good luck. ahdictionary.com
That gives an ordinary sentence a hidden history: “Perhaps I’ll be happy.” Two descendants of the same ancient idea of chance, wondering whether fortune will smile.
