Complex sentence: Selena remains the best-selling Tejano artist of all time, who continues to outsell living Tejano artists, and the last Tejano musician to have appeared on the US "Billboard" 200 chart since 2000.
Split into simpler sentences: Selena remains the best-selling Tejano artist of all time, and continues to outsell living Tejano artists. She is the last Tejano musician to have appeared on the US "Billboard" 200 chart since 2000.