Some want to use the start of his career to explain how he's this great striker waiting to happen, but there are so many examples of young player, including within United, who started bright and turned out to be average. There is very little evidence that Rashford is anything but an average talent with great physical attributes. It's still too soon to call it either way, but the red-tinted glasses that have been used on this boy since the start of his career have been nothing short of ridiculous hyperbole, and the sad part is that it's possible he's listened to some of it, to his detriment.
What is special about this boy? He has very little intelligence on the field, his touch is poor more often than not, he doesn't think ahead of the moves he makes, his finishing is poor, his crossing/corners are more miss than hit (and yet he takes corners all the time). Outside of his great physical attributes, and his heart on the field, what is so special about Marcus Rashford? I'm not going to go as far as to call him Macheda, but he hasn't shown anything to me that screams special talent or someone worth grooming for the striker position (especially with a more talented and better suited Martial on the team). So far, he is just an average player who has the odd solid game every once in a while, like any average player that plays professional football will have.
But he is still young, he may prove me and all of his doubters wrong, but right now that is less likely than the possibility that his talent doesn't nearly warrant the hype.