Not sure whether I'd go for Rashford, but the Martinelli comparisons aren't fair. Rashford scored 30 goals in all competitions in 22/23, and 17 in the Premier League, in a dysfunctional team, more or less carrying United to third place by himself. Martinelli is a nice player, we all love how hard how he runs around, but he doesn't have that kind of ability. He scored 15 in all competitions last season, and he is much more limited in what he can do on the ball – he plays at one speed, uses one foot, and relies on his industry (rather than trickery or anticipation) to beat defenders. Rashford is bigger, stronger, faster, has incredible ball-striking power and accuracy, and is silky on the ball with both feet. There's a clear difference in talent for me.
Not saying Rashford is the answer, but at a certain point, you need elite attacking talent to get to the top of the sport, and it's hard to find.