Why Pinchas was not a Cohen?
ב"ה Shalom Your question may seem shocking to some people. Isn't Pinchas the grandson of Aharon the Cohen? So why shouldn’t he be born a Cohen ? Rashi to Bamidbar 25:13 answers the question. Rashi says: Although, the Cehuna= priesthood had already been given to Aharon's descendants (See Shemot 28;41),it was given only to Aharon and his sons who had been anointed together with him and to their offspring which they would beget after they had been anointed. But Pinchas who had been born before that had not been anointed and had not yet attained the status of Cehuna until now (after the slaying of Zimri) . So too can we read in the Talmud Zevachim (101B) that Pinchas did not become a Cohen until he had slain Zimri. All the Best