Manchester United needs a striker that's consistent in scoring goals, and Nicolas Jackson isn't that type of a striker, so I won't encourage Ruben Amorim and Manchester United to go for Nicolas Jackson, who failed to perform well at Chelsea. In my opinion, instead of Manchester United signing Nicholas Jackson, they should sign Watkins from Aston Villa because Watkins is better than Nicholas Jackson.
Manchester tried with old strikers who actually helped them resolving goal scoring issues in one or two seasons but not longer than that. They have failed to find a young and talented striker who can be their long term solution on this important position and if they sign with Jackson, it seems they will make another mistake in transfer market for this position.
They actually have big problems in their club at many positions, not only the striker position, but it's realistic that they can not fix all weak positions within only one summer transfer season. However, if they continue to fail with the striker position, it's hard to believe they can succeed at other positions in their squad and their performances in coming seaon will likely be bad.