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.
Indeed, nothing should be underestimated until we see how the new season truly restarts. Amorim may be inexperienced in the Premier League, or even at a big club like Manchester United. However, Amorim has actually proven his quality for Manchester United in the Europa League recently. However, his over-focus on the Europa League has made Manchester United's performance in the Premier League less than impressive.
However, in the new season, I think all Manchester United fans will still want Amorim to lead Manchester United to at least a top-four finish. Or at least a good ranking to secure a European spot. I'm quite certain that if Amorim, who only focuses on the domestic league but doesn't manage to achieve a good enough ranking, will have to face the consequences of criticism and the like, which we're all accustomed to seeing. But as a coach, I'm quite confident that Manchester United is a club that is always patient enough to give its coaches time to build their teams.