Here's where things get a tad confusing: Spider-Man is indeed a Marvel Comics character, but Sony has had the film rights to Spider-Man. After "Spider-Man 3" in 2007, Sony rebooted the series with 2012's "The Amazing Spider-Man" and recast Tobey Maguire with Andrew Garfield. A sequel was released in 2014 and Sony wanted to create its own Spider-Man cinematic universe, but that didn't exactly go according to plan. Sony and Marvel Studios struck a collaborative deal in 2015 where Marvel could use its own version of Spider-Man in its movies, while Sony would continue to finance and distribute the films. So, now we have a Spider-Man who is in the MCU played by Tom Holland, while Sony still gets to use characters from Spider-Man comics like Venom, a character that is being played by Tom Hardy in a movie to be released in October (that is not part of the MCU).
Phew, that's a lot. Moving on.