The specific facts regarding the MCU version of Uncle Ben, and any part he might've played in Peter's decision to become a hero, have yet to be revealed
Eric Carroll, a co-producer on Spider-Man: Homecoming, said there was a Ben, whose death was implied, and they hadn't gone into trying to change his origin story, as far as Carroll had envisioned it.
ERIC CARROLL: They talk about that, absolutely. It’s not… it’s not a huge thing that I want to go into too much, but there is an acknowledgment that there was a Ben.
[...]
I mean, we’re implying he’s dead. We have not at all, again, gone into trying to change his origin story as far as I have been envisioning it. But we, just again, we thought that to keep this fun, light tone, as soon as they have to have their, like, ‘Let’s remember our dearly departed father figure’ – it derails that a little. And again, what we’re trying to tell is this sort of fun story of the kid who is doing all the wrong things for the right reasons. And once you do that, it stops becoming a sort of sun movie about a kid trying to be a kid. He’s mourning the loss of a parent.
Spider-Man: Homecoming - Uncle Ben's Role Revealed
John Francis Daley, one of the writers on Spider-Man: Homecoming, said there was going to be a scene in that film where they acknowledged Uncle Ben and his death, but they ultimately decided not to include it.
We did talk about there being a scene where [May] references him directly. It was when [Peter] was getting ready for homecoming and the wardrobe she was giving Peter was all Uncle Ben’s clothes. It was a nice moment, but we also knew that it veered away from his arc. If you’re going to talk about someone’s death, you don’t want it to be a throwaway.
Spider-Man: Homecoming writers answer some burning questions
When asked about Uncle Ben's existence around the time of Spider-Man: Homecoming's release in 2017, the director of all three MCU Spider-Man films, Jon Watts, said he thought that Peter had an Uncle Ben, but seemed unsure, and mentioned that they didn't really talk about him much.
MATT SINGER: Speaking of cans of worms you guys opened, I’m going to ask you something I also asked to Kevin Feige and see if you have the same answer: Does this Spider-Man have an Uncle Ben? Or did he have an Uncle Ben?
JON WATTS: Uh, yeah. I think so. I mean, again, we don’t get into such depth in this movie. It’s not something we really talked about that much.
MATT SINGER: Hm, all right.
JON WATTS: Yeah, I’m curious. Yeah, there’s nothing specifically referencing him.
MATT SINGER: He’s certainly not mentioned by name.
JON WATTS: I wonder.
MATT SINGER: I would think you would know, you made the movie!
JON WATTS: I know, you would think.
Jon Watts on ‘Spider-Man: Homecoming’ and Whether His Spider-Man Has an Uncle Ben
When asked the same question again around the time of Spider-Man: Far From Home's release in 2019, Watts initially said that there was "definitely" an Uncle Ben, but then appeared to backpedal somewhat, stating that "we don’t know" and that "We never specifically say anything about him [...] whether or not he’s around or not". He also said "Everything’s on the table", suggesting that they were keeping their options open.
Now Spidey is back in Far From Home and so is Watts. Once again, Uncle Ben does not appear. Apart from a single shot that makes an oblique reference to him, there’s no mention of him either. So when I got to interview Watts again, I decided would ask him the exact same question again: Did Tom Holland’s Peter Parker have an Uncle Ben? This time, Watts gave me a much more concrete, much more detailed answer.
“Yes. Definitely. Did you notice his initials on Peter’s suitcase?”
[...]
I had, because I am an incredibly large dork. But I wanted to know why Watts was so reticent about Uncle Ben the first time around and so assured this time, so I asked if anything had changed between Homecoming and Far From Home.
“We knew we weren’t going to tell an origin story, so we just avoided talking about that in too much detail,” Watts explained. “I didn’t want to reveal too much. It was a lot more sensitive of an issue to not be doing an origin story when we were talking about Homecoming ... back then, people were saying ‘Why are you making another Spider-Man movie?’ The focus was on showing people things that they had never seen before, not retelling that origin.”
[...]
So Uncle Ben definitely existed in the Marvel Cinematic Universe. But Watts was quick to add a little unsolicited ambiguity into the equation. When I noted that he is now willing to say “Yes, Uncle Ben did exist in the MCU,” he replied “Yeah. I mean, we don’t know,” and then he took a long pause before adding “We never specifically say anything about him. So whether or not he’s around or not.”
My response to that comment was probably best described as stunned silence. I didn’t ask a follow-up so much as I let out a confused “Huhhhhhh” as I pondered the possibility that Watts seemed to be implying: That Uncle Ben might not be dead in the Marvel Cinematic Universe. At that point, Watts added “Yeah. Everything’s on the table, is how I like to say it.”
Does the MCU’s Spider-Man Have an Uncle Ben? Jon Watts Says Yes
According to Kevin Feige, they wanted audience to fill in the blanks themselves, but haven't revealed the specific facts.
KEVIN FEIGE: The truth is, we want audiences to bring their own... let them fill in those blanks right now. They've seen the other films. They've read comics. They can fill that in. That was a very purposeful decision we made to not retread that ground. There are little things that are said here and there that people can read into. What the specific facts are in the past, we don't... we haven't revealed yet.
The Real Reason Marvel's Spider-Man Movie Doesn't Include Uncle Ben
In another interview, Feige made similar remarks, but was even more non-committal, again suggesting that they were keeping their options open.
MATT SINGER: Does this Spider-Man have an Uncle Ben? Or had an Uncle Ben?
KEVIN FEIGE: I love that you asked the question that way. [long pause] The answer is we allow the audience to bring in what they know about Spider-Man and plug it in themselves. What really happened, how it really happened? He got bit by a spider, he was talking to Ned about it. “Spider’s dead, Ned.” He tries to start to tell the story to Tony Stark in Civil War.
MATT SINGER: Right, and Tony shuts him down.
KEVIN FEIGE: So I do think there is some intriguing stuff for us to play with in future movies about what really happened — are we taking those things for granted? What did happen there?
Kevin Feige on ‘Spider-Man: Homecoming,’ Miles Morales, and Spidey’s Future in the MCU
In fact, none of the MCU movies strictly confirm that Peter had an Uncle Ben, what happened to him (if he did exist in the MCU), or what if any role he might've had in Peter choosing to become a hero.
The closest we got to a confirmation of Ben's existence in the MCU movies was a shot of Peter packing a suitcase in Spider-Man: Far From Home, with the initials 'BFP' on it.

And the closest we got to confirmation that Ben might have died, and that his death might have been instrumental in Peter's decision to become a hero, was the following exchange between Peter and Tony Stark in Captain America: Civil War.
TONY STARK: Why you doing this? I gotta know, what's your MO? What gets you outta that twin bed in the morning?
PETER PARKER: Because... because I've been me my whole life, and I've had these powers for six months.
TONY STARK: Mmm-hmm.
PETER PARKER: I read books, I build computers. Yeah, I would love to play football, but I couldn't then, so I shouldn't now.
TONY STARK: Sure, because you're different.
PETER PARKER: Exactly. But I can't tell anybody that, so I'm not. When you can do the things that I can, but you don't... and then the bad things happen... they happen because of you.
TONY STARK: So you wanna look out for the little guy, you wanna do your part? Make the world a better place, all that, right?
PETER PARKER: Yeah, yeah, yeah, just looking out for the little guy. That's what it is.
Captain America: Civil War (2016)
Uncle Ben was finally mentioned by name in an episode of What If...?, and his death was strongly implied.
HOPE VAN DYNE: Oh, kid. How do you do it?
PETER PARKER: See all these movies? AV club.
HOPE VAN DYNE: No. No, how do you stay so... upbeat? After everything.
PETER PARKER: Practice, I guess. My mom, dad, Uncle Ben, Mr. Stark. Now Happy. I've... I've lost a lot. But my Aunt May says... used to say, that if we don't keep smiling when they can't, then we might as well just be gone, too. And... well, they'd want us to keep going.
What If...? - S01E05 - "What If... Zombies?!"
Given everything above, it appears that the MCU version of Peter almost certainly did have an Uncle Ben, who probably passed away at some point. But we have no real confirmation that he played a pivotal role in Peter's decision to become a hero, and even his death isn't strictly confirmed.