The MCU is not canon and if you're telling me that the movie version of infinite wars is the same as it is in the comicbook then I feel sorry for you because who ever told you that is lying to you.
1. Thanos didn't kill because of some type of stupid balance of the universe theory like he did in the movie, his motive was to gain Mistress death's love.
2. Mutant were part of the infinite wars MCU versions does not include them or have them for that matter.
3. Silver surfer and Adam Warlock are the ones who lead to the down fall of Thanos during the Infinite Wars, MCU doesn't even have either of them in it.
4. Hulk doesn't run from Thanos, Thanos usually avoids the Hulk for obvious reasons.
5. Stormbreaker is Beta Ray Bills not Thor's hammer, and Thor is Erick Masterson in the comic Infinite Wars.
These are just a few examples given on why the movie is NOT canon.
Also a little side note, Earth 616 doesn't exist anymore after what Doctor Doom did in Battleworld Secret Wars.
1. The MCU is canon because it exists in its own separate universe, different timelines and events is what makes the multiverse so vast and different. It’s a official universe called Earth -1999
2. I read infinity war so you don’t have to explain the plot.
3. Earth 616 exists, did you even read secret wars? Because the fact you think it ceases to exist means you either glossed over it or didn’t complete it.
And as of late, Earth 1610 still exists as well.
Once again, this is the infinity war from the Earth - 19999 timeline, aka the MCU so it’s canon.
Marvel has a multiverse that interconnects with each other. The same reason why Miles Morales is in the 616, why Spider-Woman(Spider-Gwen) was also in the 616 and why the venomverse, Deadpoolverse and Spider-Verse exists. It’s all canon because it’s different realities infinitely being made. There’s even a universe where octavious is permanently in peter Parker’s body.
Each universe is canon unless otherwise rectonned.
616 is the main Universe and where a majority of the comics runs take place.
The other universes are also canon but exists outside of the main universe we all know.