What is the ruling on celebrating the Prophet's birthday with beneficial lessons that encourage following the Prophet's ethics and actions without innovations?

The summary of the answer: This question has been answered before. If the commemoration of the Prophet's birthday were through useful lessons connected to his ethics and biography (peace be upon him) and an exhortation to follow him, then part of following him would be not to introduce these lessons specifically for his birthday, as this has not been authentically reported from him nor from his companions (may Allah be pleased with all of them). This opens the door to innovation (bid'ah), which starts small and then grows and spreads until it reaches innovations in belief, as is the case with celebrating the Prophet's birthday. "And the best guidance is the guidance of Muhammad (peace be upon him)."