But why do these Marian apparitions always put in a go-between, and always bring the overridding attention to 'Mary'?
At Lourdes, Fatima, and Guadalupe, always the emphasis is on Mary, the "Queen of Heaven". The apparition mentions "her son" and to come to him, but people only see that Mother Mary supposedly appeared. That is not calling attention to Jesus, that is calling attention to the apparition called Mary.
I cannot explain the Marian apparitions other than to say that Mary is a Jewish Mother...and if your son was divine, you'd probably never tire of telling people about him, too! :-)