I’m so out of it, I have no idea what the marvel universe is. Is wonder woman one of them?
Going to an MCU film is like going to McDonald's rather than going to a family run restaurant. McDonald's is a pretty ok meal, but not great. The family run restaurant might be good, but it might be terrible. But at least if you pick McDonalds, you'll know ahead of time what the quality will be.
It’s the catchphrase for the world inhabited by the characters created by Marvel Comics starting in the 1960s. They were notable for having more complex characters than the then dominate DC comics. The movies do well because every age group since baby boomers grew up with them, so there’s a built in nostalgia factor. Plus some good stories at least in some of them.