Google founders couldn't spell Googol?

Um no. They could and that is what they wanted to name Google originally

Off hand, I don't remember who it was, but their first investor misspelled the name as Google on the check and they just took that as the name.

Bullshit, that domain was simply already taken. Googol.com was registered in 1995.

The average person would have spelled Googol as "Google", so it was the natural choice.