You misunderstood. The Quran is not a history book. What I mean is that the Quran has been preserved unchanged since the first moment. And For us, all people are equal. Based on this, all prophets are equally valuable. Saying that Jesus might not have been murdered does not mean devaluing him.
Saying that Jesus might not have been murdered - and saying that despite of so many historical sources confirming this historical fact - does mean devaluing him, because this way Jesus couldn't accomplish his Mission: entering afterlife, defeating Death, resurrecting Himself for the Redemption of mankind.
And this is exactly what Satan would love to hear from everyone. And Muhammad after his first revelation thought it was Satan. (Sira No. 154, Ishaq).
Everything fits like a glove. I'm sorry.