Lowly means humble in rank or importance. A lowly clerk, lowly beginnings, the lowly potato.
It is often affectionate or self-deprecating rather than dismissive — the lowly potato, a lowly apprentice — and it carries a hint of something underrated. It has a slightly old-fashioned ring. Note the trap: lowly looks like an adverb but is an adjective, in the same family as friendly, likely and lively. There is no adverb from it, which is why nobody ever writes lowlily.
1adjectivelowlyHumble in rank or importance.
“Even the lowly foot soldiers were invited to the king's victory feast.”
lowly is a quality of humbleness.
Low plus -ly, the adjectival suffix rather than the adverbial one. English uses the same ending for both jobs, which is why lowly, friendly and lively read as adverbs and are not.
Proto-Indo-European
*legʰ-
Middle English
lāh
English
low
English, today
lowly
Built from
From low + ly; compare lowly. low comes from Middle English lāh. From Middle English lah, loue, from Old Norse lágr (“low”), from Proto-Germanic lēgaz (“low; flat”), from ligjaną (“to lie; to lead”), from Proto-Indo-European légʰyeti (“to be lying down”), from legʰ- (“to lie”). 2
Etymology from Wiktionary, CC BY-SA