Not quite, no. In 2005, Feige convinced Marvel that they could do a cinematic universe from the start in order to capitalize on the fact that, unlike Spider-Man and the X-Men, they didn't share movie rights with the core Avengers, and the remaining Avengers could be negotiated. But it was such a risky gamble that Feige's boss Avi Arad was vehemently against the idea of having a series of solo films that culminate into a grand crossover and resigned in protest of this strategy in 2006. Marvel, in turn, had to negotiate a line of revolving credit with Merril Lynch in $525 million (which was the cost of several MCU movies back then, way more than 1 film) to start the modern incarnation of Marvel Studios that same year to handle this task. So no, they had every intention of using Iron Man to jumpstart the Cinematic Universe. Indeed, even before the Iron Man script was finished in 2007, Marvel Studios created a committee (including Feige, Quesada, and Bendis, and overseen by Marvel Pres. Alan Fine) to guide the creation, timeline, and maintenance of the MCU and allowing them to lay down the foundation of the MCU within the fabric of the movie, not just the after credits trailer (indeed, there are references, hints, and foreshadows abound throughout the film about the greater universe).
But that's also not to say that they couldn't focus on making Iron Man good. At the time, Marvel Studios could only focus on one project at a time given their age and lack of resources, giving Iron Man the attention it needed to become a success. At the time, Marvel Studios was a fledgling independent studio which had to prove itself in order to stay afloat. Feige, Favreau, and the other committee multitasked, but multitasking doesn't necessarily mean one suffers for the other. It means they can prioritize, which shows clearly in their work. Plus, Marvel as a publisher had the resources to allow Feige and Favreau to focus on the movie while the committee conceives the MCU, and Feige -- as studio head -- had the power to convene the committee (incl. the Marvel Pres) with Favreau and the production team in order to incorporate finalized ideas before filming started.
For reference, keep in mind that Arad left Marvel in 2006. Also, here's an article from the NYT in 2007:
https://www.nytimes.com/2007/06/18/b.../18marvel.html
Both of those predate Iron Man, and it's public record that Marvel planned to have an MCU from the start. The creation of the Marvel Studios, the game plan to convince banks to give them credit, the behind the scenes drama, the committee, and the pre-Iron Man hollywood articles all show that Feige and Favreau didn't *just* focus on Iron Man, but launching a cinematic universe and making sure a studio delivers a good product are not two mutually exclusive things.
https://en.wikipedia.org/wiki/Marvel_Cinematic_Universe <-- plus the resource links down at the bottom of the page. Be sure to check out any of the countless youtube videos of interviews by Feige and other Marvel honchos at comic cons over the years.