Doctor Strange: "You are the right person to replace Logan."
X-23: "I know there are people who disapprove... Guys on the Internet mainly."
(All-New Wolverine #4)
That stuff felt much more underplayed and not as in-your-face as it was with MCU Spidey. It only occasionally came up in conversations between Peter and MJ or in Peters' internal monolgue, but it wasn't such a main drive for his heroism as it seemed to be with MCU Peter.
And while he seemed to look up to Stark, it didn't come across like it did in the MCU where it put Peter in such a sidekick status towards Iron Man.
As far as the "rookie in a world of pros," while I'd say it's a similar standing I think in practice it was applied completely differently. Especially since Ultimate Pete didn't become as quickly embroiled in the Superhero teams of his universe as MCU Peter did.
Let's play a fun game called: MCU Peter or Ultimate Peter?
"Tony Stark rules. He Totally rules. I wonder if he read my essay. Man, I would LOVE to show him my web fluid formula. I know he would love it. It would knock his … socks … off"
" Super awesome cool!!!!...I am totally digging the new Iron Man Armor.... and that's the nicest thing anyone's said to me all week"
"You're one of the smartest men in the world, and I don't mind saying one of my all time personal heroes..."
In the case of Ultimate Peter, Tony Stark is not the major superhero guy Peter has interactions with. He had some but Tony Stark was more "cool uncle" than substitute Dad and father figure. Nick Fury was Peter's point-man in the superhero community...and Fury and Peter's dynamic was much more fraught. Peter often questioned and challenged Fury, backtalked him, certainly didn't worship the ground he walked on as he does with MCU Tony.
Like Ultimate Peter was a good bit rebellious. Like he ran into the Ultimates and this was his judgment about them:
"I mean, this is what I have to look forward to when I grow up? People being just... jerks."
— Ultimate Spider-Man, Issue 70
MCU Peter is too whitebread to voice an attitude like that. The point of Ultimate Peter as the story evolved was that he became the moral and emotional center of the entire Ultimate Universe, albeit unintentionally since the extreme makeovers and violent personality shifts in the Ultimates and the Ultimate X-Men, made Ultimate Peter by default the only decent superhero in a totally corrupt world. The whole "Death of Spider-Man" arc was about that. Despite being young, he was the guy that Johnny Storm looked up to, that Shadowcat took inspiration from when she became leader of the X-Men Post-Ultimatum.
Now obviously MCU can't go there right from the get-go since that stuff built up over many issues. But the problem is that Peter's hero-worshipping of Tony Stark doesn't make too much sense within the universe. Like Tony started out as a weapons manufacturer, and then became a, very destructive, superhero...in the same movie that Peter showed up, he's notorious for building Ultron and blamed for the destruction of Sokovia. It makes little sense that Peter would wholeheartedly admire Tony that way...and the only reason is corporate branding. In the original Civil War story, Peter started in Tony's side but then saw the whole Gulag thing and became Team Cap.
To me MCU Peter is not the character Peter Parker/Spider-Man (in the way Ultimate and 616 Peter are) but he's the company mascot Spider-Man.
He feels kind of like the Avengers' mascot because of how young he is, but since Iron Man is basically the flagship and tentpole hero of the MCU it feels like Spider-Man has to ride a little on his coattails in the MCU.
An issue that is not shared by...basically any other MCU solo hero.
Tony Stark is billionaire scientific genius who used his flying suit to help fight off an alien invasion in Peter’s city. It doesn’t really matter that he was a weapon manufacturer before becoming Iron Man or was involved in the Ultron incident. The battle of NYC is more than enough to explain why a 16 year old rookie superhero would treat Tony the way Peter does.