I think Lookman will be a big upgrade to Manchester United. He's a very good player that has all the qualities of a good winger. He's one of the kind of player Manchester United need. I believe he will fit in to their system because he's a team player and he's hardworking. I like Lookman and I will not advice him to go to Manchester United because the atmosphere there is too toxic.
It'd better if Manchester United stops to gamble for another forward. They have to put their focus onto their defensive line. They conceded a lot of goals due to the incompetency from their defensive line. They shall fully concern about how shaky their defensive line is.
It's dumb when you have a lot of forwards, but keep buy a new one without caring more to your defensive line. They can still keep Garnacho to stay much longer, then lined up some good defenders. They can get good defenders to replace their current devensive players. This is gonna be more useful instead of always focusing on the forward.
Since Amorim hands Man United has been a little more structured in terms of defense, able to utilize the abilities of Mazraoui, Ugarte, De Ligt, Martinez and even Maguire. The attack line also needs to be improved and in fact strikers like Rashford must be discarded. Garnacho still has the potential to be explored over time. The point is that some players must be discarded and replaced with fresher ones, including the back line which also deserves to be strengthened.