I found back an old article about the apocryphal Gospels and it is fascinating how the author points out that it was these numerous apocryphal texts, rather than the four canon ones, that truly shaped Jesus as a character in popular culture, folk-Christianity and peoples' minds as a whole.
It was in them that Mary was fleshed out and given parents. It was in them Joseph actually became a character of his own, existing as an individual person. It was in them that most of the episodes of the Nativity and the Flight from Egypt came from - the idea of a sacred grotto, with an ox and a donkey? That's from the apocrypha, not the canon. They are also the ones that gave the number and names of the Wise Men.
The apocryphal Gospels focus a lot, a LOT, on the figure of Mary. In fact this is very likely why they were not made canon in the first made - due to the very heated debates about the nature (and very concept) of the "Mother of God". The article (written by Marie-Françoise Baslez) points out how, when it comes to the "virginity" of the Virgin Mary, the canon just stops at "virgin conception and that's it". The apocrypha goes further by adding the concept of the "perpetual virginity" - showing a clean, painless, aetheral birth hidden by clouds and lights, and even having a midwife get her arm burned to a crisp when she tried checking if Mary was still a virgin. (She got better though - see the Gospel of James).
Another aspect that probably made them un-canonical was how they felt too much like a "hidden god" story, per the author's own word. The many "Infancy Gospels" (focused on Jesus' childhood) had him perform many miracles and acts of "magic", with angels appearing or surrounding his every moments of life, and Mary herself having sometimes the power to miraculously heal people. Which went against the canon, in which Jesus only started being able to make miracles after being baptized and starting a career as a preacher. These texts were very probably much too reminiscent of common motifs and tropes found in the adventures of half-divine heroes and reborn-deities in the mythologies of the time. (For example you have the Pseudo-Matthew Gospel which echoes the legend of Orpheus, why with all the wild beasts and plants being charmed by Jesus and trying to protect him and following him everywhere he went)
There's a lot of funny little things in these apocryphal Gospels. Like an alternate account of Jesus' resurrection where two angels actually get down from Heaven and drag Jesus' body out of his grave with his cross following him up into the sky (The Gospel of Peter) ; or a testimony by two former Limbo/Hell-inmates about how Jesus went into the Underworld, Satan tried to wrestle him, he broke the doors of Hell and set free Adam (see the Gospel of Nicodemus).
(And of course, some of the apocrypha were just condemned for heresy. Like the Gospel of Peter, which was thought of as encouraging the heresy according to which the "Incarnation" wasn't "real", as in Jesus had no real body and was not truly made flesh - by showing, for example, how he did not suffer of and barely seemed to notice his own crucifixion.)
