Are you sure that you know when Amorim took over from Ten Hag. It was close go the middle of th3 season and that means he hasn't spent up to one season. You should see the weak players that Ten Hag bought which led to his sack. How do you expect a new coach to use such players to achieve a better result. Amorim only focused more on Europa League last season and he almost won the trophy but the same weak players messed it up. I can boldly tell you that currently, United have a game pattern unlike, when Ten Hag was in charge.
Amorim also made many mistakes, he concentrated all his efforts on the Europa League and completely ignored the Premier League games, besides, if he didn’t like the players that Ten Hag bought, then what was wrong with Rashford? In any case, I think Amorim is a weak coach and I don’t believe that Manchester United will be able to show a better game in the new season. And these few transfers will not be enough to change anything significantly, and since there are not so many new transfers, he will have to rely on the players he currently has in the team.
Amorim was new and didn't understand much about the Premier League clubs which made him feel that, he can't make it to the top four because he wanted an automatic qualification to UCL. That was his target but Tottenham shattered that dreams. Therefore, I wouldn't blame him for United misfortune last season. You don't need to underestimate Amorim until, we see his efforts at the end of this upcoming season.