I do think titles are important, but,
I don't think this is the important part! Whether or not the title specifically relates to the content of the story is kinda irrelevant to whether or not it's a good title. I think the tone is super important though?
Like for a kinda out-there example, if you title your comic The Epic Fantasy of Epicness: Most Epic EVAR!!! the feel of that title is something kinda goofy that's gonna laugh at itself. So if you have a parody, or comic full of silly fantasy jokes, it fits okay, even if your fantasy characters never actually go on an adventure. The content might not match, but the tone does.
On the other hand, if you try to have an actual, seriously epic adventure with a struggling hero and a dark, growing evil, that title is gonna hurt you a lot. People who want a real serious adventure will assume a series titled "Epic Fantasy of Epicness" isn't for them, and people who think that title sounds interesting are less likely to be there for a serious story. Even though your story is literally an epic fantasy, that title doesn't fit at ALL, because the tone is wrong.
I think it's usually a lot more subtle than that -- it's hard to put your finger on what makes one title sound way too goofy and another sound exactly the right amount of goofy, for example, so I think after you've made sure it's not too complicated and googles okay, you just gotta go with what feels right for your story!