Honestly, if people can invest in Homer Simpson, then you're good.
In fact, lots of stories are written with the main character being stupid or sheltered (gestures widely to Frodo Baggins as one example). And the dude who went before Frodo from that series, blanking on his name, wanted literally to just stay home and eat and drink and read a book in peace.
But also, that's not an unrealistic worry. One of my friends read a story of mine and didn't like MC1 until 50k words in, and up to that point they liked MC2 better. Motivations and what they do are essential.