فِي الْبَيْتِ رَجُلٌ.
There is a man in the house.
Placing the prepositional phrase first is an ordinary and idiomatic structure with an indefinite subject. Its position alone does not entail that a man exists in this house and nowhere else.
Fronting can acquire contrastive or focusing force when there is evidence of correction or opposition. Do not replace a natural syntactic arrangement with an unsupported claim of exclusive restriction.