What does "America is back" mean exactly?

I know what Joe Biden and Antony Blinken, his secretary of state, were trying to say when they coined the phrase, "America is back" which has been doing the rounds a lot recently. I guess what they were hoping to tell the world was that that awful man Trump has now gone and the good guys are back in charge who know how to be nice and diplomatic and consensual and collaborative...and predictable. After four years of a rumbustuous make-it-up-as-you-go-along president, we now have an American leader in charge whom allies around the world, and especially in Nato, can feel relaxed about. The smile is back on the face of everyone who had to put up with Trump's petulance. But there is one thing that worries me. Bold politics and world-influencing leadership don't necessarily come with niceness. Trump went over the top by thinking he knew better than anyone and told them so, and as a result, infuriated pretty well every leader in the world at some point, allies especially. But my God, he didn't half put governments on their mettle, and that's not always a bad thing. Being terribly agreeable doesn't always get the best results. This is why I raise concerns about "America is back". Let's look at it from other countries' point of view. Iran, for example. The ayatollahs and the nasties of the Islamic Revolutionary Guard Corps hated Trump because he punished them with more and more sanctions until their economy stuttered and they must always have had in the back of their minds that Trump might wake up one morning and order the Joint Chiefs to bomb the hell out of their nuclear facilities. There is no way Biden is going to order an attack on Iran's nuclear sites. He has offered talks and is considering lifting some sanctions to encourage them to stick to the much-maligned 2015 Obama-inspired Iran nuclear deal. After four years of insults from Trump, the nasty element of Iran - I'm not talking here about the ultra-smooth foreign minister Mohammed Javad Zarif - will be thinking to themselves, "Great, let's screw Biden until we get all sanctions lifted". Will Tehran in return scrap all dreams of owning nuclear weapons and give up masterminding aggression in the Middle East and elsewhere? No, I don't think so. Tehran got what it wanted with that other nice man, Barack Obama. So in their eyes, "America is back" is probably viewed as a gift for some devious manipulation. And what thinking is going on behind closed doors in Moscow and Beijing and Damascus and Pyongyang? Relief there is a decent bloke in charge in the White House and anticipation of a new era of sweet-smelling diplomacy, or strategic plotting to exploit what they might think will be an era of nice but dull Biden.