Rashford isn't so good in the central attacking position, he is better on the left side of attack, and Erik ten hag would know that if he wants to harness the full potential of his best attacker, he'd have to play him in his favorite position.
Having said that, Harry Kane doesn't seem to be serious about leaving Spurs, if he is; he would have handed in a transfer request, other than that, it would be impossible for Manchester United to try and reach an agreement with Spurs/Daniel Levy for Harry Kane. I don't know much about Hojlund, but i think Atalanta are asking for too much for the Danish international, if they don't reduce their valuation of the striker, Manchester United might be forced to walk away from the deal.
Rashford played as a centre-forward in 19 matches last season. His statistics were like 11 goals and 5 assists. It is impressive really but I still think the same as you. He should be preferred as a left winger instead which is his natural position. In this situation there is really a serious need for a striker for them.
Martial can't be trusted much. He can't give the expected effort to his team. Kane would be a really great transfer of course. However his future is still ambiguous. He isn't pushing too much to leave Tottenham now. He is just okay if he leaves for free next summer as well.
But it looks like Levy will think of letting him go more seriously as he is in his last year of his contract.