With United struggling to click under Erik ten Hag's successor, major coaching names have again been linked with summer moves to Old Trafford.
But speaking with The Times, Ratcliffe insists Amorim has his full backing.
He said, "I think he’s done a great job in the circumstances, frankly, with the squad that he’s had available. The fact he came in mid-season.
"Everybody expects miracles overnight. It’s not the way, not real life in my view. I mean, you saw the performance yesterday (Sunday's 1-1 draw with Arsenal).
"It was, I thought, a really impressive performance. They could not have worked harder. They couldn’t have been more committed.
"And if you looked at the names on the bench, there weren’t many you recognised, were there? Half the squad’s missing for Ruben.
"If you look at the top eight players in terms of salaries in Manchester United, 50 per cent of those are not available to Ruben.
"You’ve got Mason Mount, you’ve got Luke Shaw, Marcus Rashford has gone, and Jadon Sancho. And he’s got a bunch of other injuries as you know, so I think he’s done a fantastic job.
"I think coaches are emotional and Ruben’s no exception to that. And he’s a young coach. And he’s not perfect. You know, he’s not a guy who… he’s got to be good on the stage, but we want him to be good on the grass. And part of that is life on the stage, isn’t it?
"You know, you’re a young guy, you’ve come into the Premier League for the first time in your life, you’ve come in mid-season, it’s not your natural language.
"You have to give the guy a bit of a break. I mean, give me a hard time, I have no problem with that. But give Ruben a break. I think he’s a good guy, he’s working hard and I think he’s doing a great job."
Asked if he believes Amorim can win trophies as United manager, Ratcliffe concluded: "Yeah I do, honestly.
"I really, really like Ruben. He’s a very thoughtful guy. Every time I go to the training ground, I speak to Ruben.
"I sit down and have a cup of coffee with him and tell him where it’s going wrong, and he tells me to f*** off. I like him."