I think the bible does make it fairly clear that God is more interested in the state of our heart than the outward things we do though.
I think so too.

I don't think I have to perform any rituals, but I do like some of them (communion for example) to remind me of their significance.

"Is Christian humanity grown up enough to live without the rituals God asked for in the cradle of Christianity?"

I sincerly hope so! I think the Word of God should be so ingrained in our hearts that we can live the way we are meant to without having to perform a ritual. I think the rituals are a nice way of recognising each occasion they are meant for.

Sorry for being a bit all over the place, it is my bedtime!