No, a house that has no ventilators is not a safe or healthy house to live in.
(i) The air circulation is not there in such a house. So, it has no fresh air.
(ii) Warm air is lighter than cold air hence warm air passes out of your home through ventilators.
Accordingly, without ventilators, warm air will not pass out, and the house will remain warm.
Thus, without ventilators, the house will become uncomfortable to live in.