From the island meadow
Insley is an English surname-turned-given-name likely derived from a place name. It combines the Old English elements 'eg' (island or dry land in a marsh) and 'leah' (clearing or meadow).
Less common today
Insley isn't in the latest US Top 1000. It last peaked at #8,911 in 2020.
US births per 5-year period, 1990βpresent (SSA data).