Complex sentence: Michael Llewelyn Davies (16 June 1900--19 May 1921) was--along with his four brothers--the inspiration for J. M. Barrie's characters Peter Pan, the Darling brothers, and the Lost Boys.
Split into simpler sentences: Michael Llewelyn Davies (16 June 1900--19 May 1921) was the inspiration for Peter Pan. Davies and his brothers, not only inspired J. M. Barrie's characters Peter Pan, but also the "Darling brothers", and the Lost Boys.