So, aged 27 coming from a "lower", non CL playing club, we have about 3 or 4.
The chances are low.
Here is what you said in case you forgot, and you did not specify that they must be 27 yo or above so I put examples starting from 25 :
Besides, frankly, football back then, 30 years ago, was not something you can compare with now.
Name me 5 players who having never played for a top 5 club in Spain, Italy, France or Germany have then gone on to play at a top 5 club in England or those countries and been successful?
Honestly, I have watched Amrabat and have never been convinced he's a world class player, good enough to help a United win the league or Champions league. If he was, he wouldn't have been at Fiorentina, Hellas Verona and Club Brugge for the past 5 years.
Mahrez - Never played in top 5 clubs before he joined City and have been successful. No matter what you wanna say about Leicester, they are not a top 5 club
Kante - Same as above
Vardy - Same as above
Drogba - Joined Chelsea when he was 26 and Marseille when he was 25.
Luca Toni - You don't think so? What? Do you even know who he is? He spent the bulk of his early career playing for Serie B teams before joining Fiorentina when he was 28, and Fiorentina is not a top 5 club in Italy. He only joined Bayern when he was 30, and was the golden boot winner while winning the title.
Klose - Not sure what I mean or do you not even know who Klose is? He played for Kaiserslautern until he was 26 before he joined Bremen. Kaiserslautern is not a top 5 club in Germany. He joined Bayern when he was 28.
Raphinha - Leeds is not a top 5 club...
Van Dijk
Luis Diaz - Porto is not a top 5 club in Spain, Italy, France or Germany.
Falcao - Falcao only joined Atletico when he was 25.
Wijnaldum
Senna - Who? I guess you don't know too much about anything outside PL. Euro 2008 winner and captain of Villarreal for a decade when they were CL regulars.
Ian Wright
Quagliarella - Joined Juventus when he was 27 and won 3 league titles. Never played for any big clubs in Italy prior to that and was nicknamed Mr. Dreamgoal.
Milito
Julio Cesar - Hardly a big success? 5 league titles including a treble with a total of 14 cups won with Inter, and was nominated for Ballon D'Or. Who cares if he ended his career in QPR?
Fernandinho
Henrikh
Willian - 25
Deco - Porto is not a top 5 club in Spain, Italy, France or Germany.
Carvalho - Porto is not a top 5 club in Spain, Italy, France or Germany.
Thiago Silva - Joined Milan when he was 25.
Vidic - 25
Ji Sung
RVN - 25
Bruno
Like others have said, Amrabat is not here to be the undisputed starter. He is here to provide cover for Casemiro and for us to play a more defensive double pivot if needed. Playing Bruno for 60 games a season is not sustainable, so there might be times where he will be rested and Amrabat can slot into one of the midfield positions and push Mount forward. The referees have also shown us last season that they will red card Casemiro if they get a chance, so signing Amrabat means we will not have a drastic fall in our midfield quality when Casemiro is suspended. We do not have a single midfielder that can play in Casemiro's position at the moment, as we should all know by now that McTominay is simply not that person. He is not world class and never will be, but he covers for our midfield nicely as we are sorely lacking someone who can sit deep as soon as Casemiro is out of the team. Our double pivot of Casemiro + McTominay/Eriksen/Fred last season simply gets overrun whenever we play other top 6 teams or even Brighton/Brentford, mainly due to Eriksen being gassed out after first half while McTominay and Fred is too poor with the ball under pressure. Amrabat has very good passing stats under pressure as well as progressive carries from midfield, so he can relieve a lot of pressure and be a passing outlet.
For the quoted price of 25m, he is a decent signing that provides good cover for our current midfield options. He doesn't need to be world class, he just needs to fill in the gaping hole in our midfield whenever one of our current starters need a rest or is suspended. With the amount of games that we are playing every season, he will easily play around 30 games while allowing us to rotate when required.