The Cambridge Latin books are quite good, and presented with a lot of historical background, which adds interest.
Gwynne’s Latin is also a nice introduction, especially the first section that sets out all the benefits of a Latin education. It does require discipline, though, as it is quite grammar heavy from the start.
For young children, the book “Minimus” introduces Latin in an engaging way and is good for sparking interest. It gets them speaking simple Latin phrases from the beginning, with the grammar building up slowly over time. The book follows a family in Roman Britain just after the time of Christ. Later chapters of the book do include some pagan references, but I like that the start of the book places the timing of events by reference to Christ.