What is the importance of nouns?

Importance of nouns are that, it helps us to realise almost everything in sentenses which objects we talk about therefore if there wasn't nouns then we wouldn't understand things properly in writings.

How do they affect our everyday lives?

It affects our lives everyday for naming things, like school and boys, etc. It helps to make easier to us to call things so everyone knows what we talking about without having to describe them so much about it.

Would the English language be limited without nouns?

I think it will be limited totally, because nouns are the most of the things which English speakers use to tell and describe things every daily life.

Why or why not?

It's because they are the words that starts everything like adverbs, verbs, adjective, etcs., to therefore if there isn't a noun then these followings of other kinds wouldn't be existing at all.

How do nouns affect other languages?

They affect other languages almost same way as English but not as much as it would metter, if nouns wouldn't have been existed in first place.