Is there ever anything in MCU that hints at how Spider-Man got his powers? I know that he first appeared in Captain America: Civil War, and he already had his powers. I was wondering if there is ever anything about how he got his powers for example if he comments on having being bitten by a spider or anything.
Peter was bitten by a spider and that’s what gives him his powers but not his web shooting ability.
Ned: You got bit by a spider? Can it bite me? Well, it probably would’ve hurt, right? You know what? Whatever. Even if it did hurt, I’d let it bite me. Maybe. How much did it hurt?
Peter: The spider’s dead, Ned.
He uses web shooters rather than creating webs like some of the previous versions. We see him mixing a solution in class and Tony comments on how good the mix is at one point.
Tony Stark: Yeah. Look at you go. Wow! Nice catch. 3,000 pounds, 40 miles an hour. That's not easy. You got mad skills.
Tony Stark: You know what I think is really cool? This webbing. That tensile strength is off the charts. Who manufactured that?
Peter Parker: I did.
Tony Stark: Climbing the walls, how you doing that? Cohesive gloves.
Peter Parker: It's a long story. I was uh…
Tony Stark: Lordy! Can you even see in these?
Peter Parker: Yes. Yes, I can! I can. I can-I can see in those. Okay? It's just that… when whatever happened, happened… it's like my senses have been dialled to 11. There's way too much input, so… they just kinda help me focus.
Captain America: Civil War
It’s also worth noting however that the directors never really wanted to do an origin story again, so we’re only ever going to get hints at it.
"We never talked about showing it, because the MO was always to not show anything we've seen before," Watts said. "If anything ever felt slightly familiar, to try to figure out if there's a way to avoid it or tackle it in a different way. But that was something that definitely felt like we've seen that before."
By now, a third Uncle Ben death in cinema in less than 20 years would be redundant. "That's why," Feige said, regarding the choice to skip the scene in Spider-Man: Homecoming. "You didn't really have to ask," Pascal added.
The Marvel Spider-Man Far From Home: Prelude comic indicates that he was "bitten by a genetically altered spider". There's no mention of radioactivity.
Peter Parker was bitten by a genetically altered spider and gained the proportional speed, strength, and agility of a SPIDER, adhesive fingertips and toes, and the precognitive awareness of danger called "SPIDER-SENSE"!
All we know is Peter was bit by a spider. He doesn't really discuss it more than that in the MCU
NED: You got bit by a spider?
Ned knows Peter is Spider-Man in the movie. Peter is trying to ignore Ned in the scene. This scene appears to be the only time the spider bite is referenced.