where did most indentured servants come from before they came to america?

Answer 1

The vast majority came from the British Isles - English, Scots, or Irish.

Answer 2

Europe 'dumped' its multitudes upon American shores and more than a few flew the nest due to Religious Unrest so any suggestion that a majority were of the Isles misses by a mile. Many may have spent a generation or two hosted by Prosperous Britain then as now a powerhouse siphoning surplus people from East and shipping them West across the Atlantic.
One would be surprised how many of these indentured servants were 'suspected' Jews flowing from the Netherlands and Flanders and the German States. Some stated they were Lutherans and ran with the prevalent way of saying prayers and singing hymns.....

Later when the French cleaned house of Huguenots a lot of them sold themselves for a passage to America and both parties prospered as a result. Through no fault of their own a lot of people find themselves 'homeless' which in the days of American Colonization (ie the rape & destruction of Native cultures people). These people came from across the face of Europe & England but the balance would have to be tilted to Netherlands & Flanders. Even the Pilgrims tried the Netherlands before heading for destinity in Massachusetts.

///--------O . u . O ---------- \\\ Peace................................

Answer 3

Ireland and Scotland - hands down.