Why do Muslims deny that Christ came as a savior for the redemption of humanity?

The Christians believe that the doctrine of redemption through the crucifixion of Christ is fundamental to their religion, and that its invalidity would dismantle the entire Church. A question arises regarding the universality of this redemption: Is it for all humanity or specific to believers and the baptized? Christ was sent specifically to the Children of Israel and did not redeem all humanity, as he did not heal the daughter of the Canaanite woman, though he was able to. There is no inherited sin, and every soul bears only its own burden, as stated in the Holy Quran: ﴿وَلا تَزِرُ وَازِرَةٌ وِزْرَ أُخْرَى﴾ (Fatir: 18), and this is also affirmed in the Book of Ezekiel: "The soul who sins shall die." Repentance is the way to erase sin, and God accepts those who repent, "Whoever is slowed down by his deeds will not be hastened by his lineage." Christ emphasizes in the Gospel the importance of good deeds for entering the Kingdom of Heaven, not merely words, and that every soul will be recompensed for what it has earned. Adolf Harnack observes that the disciples' epistles were devoid of the belief in salvation by redemption and made salvation dependent on works. Contradictions are evident in the doctrine of redemption, and Islam calls for a return to pure monotheism, "a word common to you and us," which contains no enigma.