Final answer:
The main reasons the Muslims did not win the first crusades were due to internal conflicts, confusion about the goals of the crusaders, and the assassination of Imad al-Din Zengi.
Step-by-step explanation:
One of the main reasons the Muslims did not win the first crusades was due to the internal conflicts among them and their confusion about the nature and goals of the crusaders. Initially, the Muslims were taken aback by the success of the Christian crusaders, but they quickly adapted and prevented many of the newly arriving knights from reaching their destination. Additionally, the assassination of Imad al-Din Zengi, a Turkic aristocrat who was praised as a defender of Islam, posed a serious threat to the remaining Crusader States, weakening the Muslim response.