C++ print template container error (error: ambiguous overload for 'operator<<') understanding?

I want to write template function which can print container like std::vector, std::list.

Below is my function, just overload <<.

template<typename Container>
std::ostream& operator<<(std::ostream& out, const Container& c){
    for(auto item:c){
        out<<item;
    }
    return out;
}

Test code as below:

And I want to add a space string in each value, so I change the function to:

template<typename Container>
std::ostream& operator<<(std::ostream& out, const Container& c){
    for(auto item:c){
        out<<item<<" ";
    }
    return out;
}

Then it get error:

merror: ambiguous overload for 'operator<<' (operand types are 'std::basic_ostream<char>' and 'const char [2]')
         out<<item<<" ";

I know << can output common type like.

int a = 0;
double f = 0.3;
std::string s = "123";
std::cout<<a<<f<<s<<std::endl;

So Why get the above error ? And is there any way to solve it?

I have see this question Ambiguous overload for ‘operator<<’ in ‘std::cout << but I still can't understand clearly.