There's both over-rating and under-rating of Greenwood going on in this thread.
No, if he was still at United this season he wouldn't walk into the team, or be the best forward at the club. He hadn't kicked a ball for 18 months, that has had a huge impact on his development and it's uncertain that he'll ever hit the heights he could have done.
But that's also the thing, this "He was never all that anyway" attitude is mental beyond belief. He was a fantastic talent and the sky really was the limit for him. As an 18 year old in 2018-19 he scored 17 goals in 49 games, 1 in 2.9 games. Compare that to other 18 year old forwards who were playing regular Premier League football.
Rooney? 2003/04 he was 18 and scored 9 in 40, 1 every 4.4 games.
Owen? 1997/98 he was 18 and scored 23 in 44, 1 every 1.9 games.
Ronaldo? 2003/04 he was 18 and scored 6 in 40, 1 every 6.7 games.
Anelka? 1997/98 he was 18 and scored 9 in 40, 1 every 4.4 games.
Stirling? 2012/13 he was 18 and scored 2 in 36, 1 every 18 games.
Fowler? 1993/94 he was 18 and scored 18 in 34, 1 every 1.9 games.
Owen and Fowler have him beat, however both playing as out and out strikers. Greenwood played as a winger and yet had a better ratio than all the other top young forwards, better than Rooney's and vastly better than Ronaldo's.
I'm not saying he was as good as Rooney or Ronaldo but he honestly had the world at his feet, and if it wasn't for you know what then I'm certain he'd be a 30+ a season forward. Also, as 18 year olds he was substantially better than Saka, it's more weird revisionism to even try and claim otherwise.