The word humble was borrowed in the late 1200s from Old French, where it was spelled umble, umele, humle, and also humble, but held the same definition. That's from Latin humilis, which could mean "lowly" but more literally may be interpreted as "on the ground". The root there is humus, or "earth", which (by way of Proto-Italic) comes from the Proto-Indo-European word degom, also "earth". Humilis, through Old French umilite, is also the root of the word humility, but my favorite descendant of the word is omerta, the Mafia's code of obedience and secrecy. Apparently that used to mean "humility" as its earlier form umilta (an allusion to a mafioso's loyalty to the gang leader), which also traces to the Latin word. All three words have trended upwards in usage in recent years.
Adam Aleksic, a rising sophomore studying linguistics and government at Harvard University, has been described as the internet's sixth most famous etymologist. He also has disturbing interests in politics, vexillology, geography, board games, conlanging, and law.