MistaT I think the main feature of Jesus's game that "helped" the likes of Martinelli or our left 8 is that Jesus makes obvious, front foot runs and draws defenders with him, creating space.
As a "space finder" who unexpectedly occupies different areas or runs different channels, drifting away from defenders rarely on the ball, Havertz's game doesn't help Martinelli in that way: Gabi's man seldom has anything on his mind other than stopping him.
On the other hand, Ødegaard has played some of his best footy with Havertz.
My take for a while has been that a 9 who is both a focal point and an obvious goal threat in possession (at Saka's level would be amazing) would take us up a gear across the whole front three.