Answer:
Because Revere presented the British as the culprits for the Boston Massacre, while Pelham presented the same event more impartially.
Step-by-step explanation:
Revere used Pelham's work as an inspiration for his painting on "The Bloody Massacre on King Street" where he portrayed the Boston Massacre when British guards opened fire on American cycles.
Pelhan never had his work valued, or was at least credited for it, while Revere had his work valued and studied until today. This probably happened because Pelhan's work presented the event impartially, while Revere placed the British as the main culprits for everything that happened.