Could "Rather = Little bit" be true? [closed]

You are looking at two different meanings of rather.

In 'It's rather blue than green', rather means instead of, as opposed to. The object can better be described as blue than as green.

In your other sentences, rather means somewhat, to a certain extent. You could say "The rules are a [little] bit complicated." (A bit is more usual than a little bit.)

"The question was a [little] bit difficult" is possible, but we wouldn't say "It was a bit difficult question."

We wouldn't say "I've always [a] little bit liked Charlie", and "I like Charlie a little bit" sounds as though you don't really like him much at all. "I rather like" sounds much more positive.